| **Long-term Debt - Textual (Details)**                                                                     | 1 Months Ended | 3 Months Ended | 12 Months Ended |              |                |               |               |               |               |                 |
|------------------------------------------------------------------------------------------------------------|----------------|----------------|-----------------|--------------|----------------|---------------|---------------|---------------|---------------|-----------------|
||
| **Debt Instrument [Line Items]**                                                                           |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Loss on early extinguishment of debt                                                                       |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   | $ 7,400,000 | $ 22,400,000 | $ 13,200,000 |   |   |   |   |   |   |   |
| Senior secured leverage ratio maximum                                                                      |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   | 1.75 |   |   |   |   |   |   |   |   |   |
| Repayments made on debt                                                                                    |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   | $ 202,100,000 | $ 597,400,000 | 302,600,000 |   |   |   |   |   |   |   |
| Capital Lease Obligations [Member] | Minimum [Member]                                                      |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| **Debt Instrument [Line Items]**                                                                           |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Effective interest rate (percent)                                                                          |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   | 2.00% |   |   |   |   |   |   |   |   |   |
| Capital Lease Obligations [Member] | Maximum [Member]                                                      |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| **Debt Instrument [Line Items]**                                                                           |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Effective interest rate (percent)                                                                          |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   | 11.00% |   |   |   |   |   |   |   |   |   |
| Senior Notes [Member]                                                                                      |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| **Debt Instrument [Line Items]**                                                                           |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Redemption price, (percent)                                                                                |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   | 101.00% |   |   |   |   |   |   |   |   |   |
| Convertible Preferred Stock [Member]                                                                       |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| **Debt Instrument [Line Items]**                                                                           |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Shares exchanged for convertible debt (shares) | shares                                                    |           |           |            |         |           |          |          |          |          |            |   | 257,110 |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Convertible debt dividend rate (percent)                                                                   |           |           |            |         |           |          |          |          |          |            |   | 6.50% |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Revolving Credit Facility [Member]                                                                         |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| **Debt Instrument [Line Items]**                                                                           |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Repayments made on debt                                                                                    |           |           |            |         |           |          |          |          |          |            |   |   |   | $ 195,000,000 | $ 45,000,000 |   |   |   |   |   |   |   |   |   |   |   |   |   |
| 5.75% Senior Notes Due 2025 [Member] | Senior Notes [Member]                                               |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| **Debt Instrument [Line Items]**                                                                           |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Aggregate principal amount                                                                                 |           |           |            |         | $ 350,000,000  |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Net proceeds for offering                                                                                  |           |           |            |         | $ 344,000,000  |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Debt instrument maturity date                                                                              |           |           |            |         | Sep. 15,  2025 |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Effective interest rate (percent)                                                                          |           |           |            |         | 6.00%          |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Debt instrument interest rate (percent)                                                                    |           |           | 5.75%           |         |           |          |          |          |          |            |   |   |   |   |   |   | 5.75% |   | 5.75% | 5.75% |   |   |   |   |   |   |   |   |
| The Credit Agreement [Member]                                                                              |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| **Debt Instrument [Line Items]**                                                                           |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Amounts outstanding under letter of credit facility                                                        |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   | $ 34,200,000 |   | $ 33,300,000 | $ 34,200,000 |   |   |   |   |   |   |   |   |
| The Credit Agreement [Member] | Term Loan Facilities [Member]                                              |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| **Debt Instrument [Line Items]**                                                                           |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Credit facility borrowing capacity                                                                         |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   | 500,000,000 |   |   |   |   |   |   |   |   |   |
| Percentageof aggregate principal amount outstanding (percent)                                              |           |           |            |         |           |          | 1.25%         |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Commitment fee (percent)                                                                                   |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   | 0.375% |   |   |   |   |   |   |   |   |   |   |   |
| Payment limit under the credit agreement's negative covenant                                               |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   | $ 200,000,000 |   |   |   |   |   |   |   |   |   |
| Proceeds from credit facility                                                                              |           |           |            |         | $ 125,000,000  |          |          |          | $ 375,000,000 |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Remaining capacity under credit facility                                                                   |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   | $ 125,000,000 |   |   |   |   |   |
| The Credit Agreement [Member] | Federal Funds Effective Swap Rate [Member] | Term Loan Facilities [Member] |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| **Debt Instrument [Line Items]**                                                                           |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Spread on variable rate (percent)                                                                          |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   | 0.50% |   |   |   |   |   |   |   |   |   |   |   |
| The Credit Agreement [Member] | LIBOR [Member] | Term Loan Facilities [Member]                             |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| **Debt Instrument [Line Items]**                                                                           |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Spread on variable rate (percent)                                                                          |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   | 2.00% |   |   |   |   |   |   |   |   |   |
| The Credit Agreement [Member] | Scenario, Forecast [Member] | Term Loan Facilities [Member]                |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| **Debt Instrument [Line Items]**                                                                           |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Maximum leverage ratio under the financial covenants                                                       |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   | 4.25 |   |   |   |   |   |   |
| The Credit Agreement [Member] | Letter of Credit [Member]                                                  |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| **Debt Instrument [Line Items]**                                                                           |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Credit facility borrowing capacity                                                                         |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   | $ 260,000,000 |   |   |   |   |   |   |   |   |   |
| The Credit Agreement [Member] | Revolving Credit Facility [Member]                                         |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| **Debt Instrument [Line Items]**                                                                           |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Credit facility borrowing capacity                                                                         |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   | 600,000,000 |   |   |   |   |   |   |   |   |   |
| Amounts drawn under credit facility                                                                        |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   | $ 130,000,000 |   | $ 152,000,000 | $ 130,000,000 |   |   |   |   |   |   |   |   |
| Applicable interest rate under credit facility (percent)                                                   |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   | 2.30% |   | 2.70% | 2.30% |   |   |   |   |   |   |   |   |
| Proceeds from credit facility                                                                              |           |           |            |         |           |          |          |          | 325,000,000   |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| 2014 Credit Agreement [Member] | Term Loan Facilities [Member]                                             |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| **Debt Instrument [Line Items]**                                                                           |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Credit facility borrowing capacity                                                                         |           |           |            |         |           |          |          |          | 450,000,000   |            |   |   |   |   |   |   |   |   |   |   | 450,000,000 |   |   |   |   |   |   |   |
| Senior secured leverage ratio maximum                                                                      |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   | 4.25 |   | 1.75 | 4.25 |   |   |   |   | 1.75 |   |   |   |
| Maximum leverage ratio under the financial covenants                                                       |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   | 4.50 |   |   |   |   |   |   |   |   |   |
| Amounts drawn under credit facility                                                                        |           |           |            |         |           |          |          |          |          | $ 75,000,000    |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Repayments made on debt                                                                                    |           |           |            |         |           |          |          | $ 250,000,000 |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| 2014 Credit Agreement [Member] | Letter of Credit [Member]                                                 |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| **Debt Instrument [Line Items]**                                                                           |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Credit facility borrowing capacity                                                                         |           |           |            |         |           |          |          |          | 260,000,000   |            |   |   |   |   |   |   |   |   |   |   | 260,000,000 |   |   |   |   |   |   |   |
| 2014 Credit Agreement [Member] | Revolving Credit Facility [Member]                                        |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| **Debt Instrument [Line Items]**                                                                           |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Credit facility borrowing capacity                                                                         |           |           |            |         |           |          |          |          | $ 600,000,000 |            |   |   |   |   |   |   |   |   |   |   | $ 600,000,000 |   |   |   |   |   |   |   |
| 7.25% and 7.75% Senior Notes due 2018 and 2022, Respectively [Member] | Senior Notes [Member]              |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| **Debt Instrument [Line Items]**                                                                           |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Redemption price, (percent)                                                                                |           |           |            |         |           |          |          |          |          |            |   | 103.00% | 103.00% |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Aggregate principal amount                                                                                 |           |           |            |         |           |          |          |          |          |            |   |   |   |   | 120,000,000 |   |   |   |   |   |   |   |   |   |   |   |   | $ 525,000,000.0 |
| Net proceeds for offering                                                                                  |           |           |            |         |           |          |          |          |          |            |   |   | $ 1,900,000 |   | 122,000,000 |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Repayments made on debt                                                                                    |           |           |            |         |           |          |          |          |          |            |   | $ 60,000,000 | 64,500,000 |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Principal amount of debt retired                                                                           |           |           |            |         |           |          |          |          |          |            |   | 58,100,000 |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| 7.25% Senior Notes Due 2018 [Member] | Senior Notes [Member]                                               |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| **Debt Instrument [Line Items]**                                                                           |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Redemption price, (percent)                                                                                |           |           |            |         |           |          |          |          |          | 103.625%        |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Aggregate principal amount                                                                                 |           |           |            |         |           |          |          |          |          |            |   |   |   |   | $ 60,000,000 |   |   |   |   |   |   |   |   |   |   |   |   | 275,000,000.0 |
| Debt issue price as percentage of principal (percent)                                                      |           |           |            |         |           |          |          |          |          |            |   |   |   |   | 103.25% |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Repayments made on debt                                                                                    |           |           |            |         |           |          |          |          |          | $ 281,000,000   |   |   | 33,500,000 |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Debt redeemed                                                                                              |           |           |            |         |           |          |          |          |          | $ 271,400,000   |   | 30,200,000 |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Debt instrument maturity date                                                                              |           |           |            |         |           |          |          |          |          | Oct.  01,  2018 |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Effective interest rate (percent)                                                                          |           |           |            |         |           |          |          |          |          | 7.50%           |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| 5.75% Senior Notes Due 2024 [Member] | Senior Notes [Member]                                               |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| **Debt Instrument [Line Items]**                                                                           |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Aggregate principal amount                                                                                 |           |           |            |         |           | $ 350,000,000 |          | $ 400,000,000 |          |            | $ 175,000,000 |   |   | 275,000,000 |   |   |   |   |   |   |   |   |   | $ 175,000,000 |   |   |   |   |
| Debt issue price as percentage of principal (percent)                                                      |           |           |            |         |           | 100.50%       |          | 102.00%       |          |            | 103.625% |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Net proceeds for offering                                                                                  |           |           |            |         |           | $ 351,000,000 |          | $ 406,000,000 |          |            | $ 182,000,000 |   |   | $ 270,000,000 |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Debt instrument maturity date                                                                              |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   | Nov.  01,  2024 |   |   |   |   |   |   |   |   |   |   |
| Effective interest rate (percent)                                                                          |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   | 5.80% |   |
| Debt instrument interest rate (percent)                                                                    |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   | 5.75% |   | 5.75% | 5.75% |   |   |   |   |   |   | 5.75% |   |
| 7.75% Senior Notes Due 2022 [Member] | Senior Notes [Member]                                               |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| **Debt Instrument [Line Items]**                                                                           |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Redemption price, (percent)                                                                                | 102.583%       |           |            | 103.875%     |           |          |          |          | 103.00%       |            |   |   |   |   |   | 103.875% |   |   |   |   |   |   |   |   |   |   |   |   |
| Aggregate principal amount                                                                                 |           |           |            |         |           |          |          |          |          |            |   |   |   |   | $ 60,000,000 |   |   |   |   |   |   |   |   |   |   |   |   | $ 250,000,000.0 |
| Debt issue price as percentage of principal (percent)                                                      |           |           |            |         |           |          |          |          |          |            |   |   |   |   | 103.50% |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Repayments made on debt                                                                                    | $ 78,000,000   |           |            | $ 52,000,000 |           |          |          |          | $ 26,000,000  |            |   |   | $ 31,000,000 |   |   | $ 104,000,000 |   |   |   |   |   |   |   |   |   |   |   |   |
| Debt redeemed                                                                                              | $ 76,000,000   | $ 50,000,000   | $ 50,000,000    | $ 50,000,000 |           |          |          |          | $ 25,100,000  |            |   | $ 27,900,000 |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Effective interest rate (percent)                                                                          | 7.90%          |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| 5.125% Senior Notes Due 2023 [Member] | Senior Notes [Member]                                              |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| **Debt Instrument [Line Items]**                                                                           |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Aggregate principal amount                                                                                 |           |           |            |         |           |          | $ 300,000,000 |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Net proceeds for offering                                                                                  |           |           |            |         |           |          | $ 295,000,000 |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Effective interest rate (percent)                                                                          |           |           |            |         |           |          | 5.40%         |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Debt instrument interest rate (percent)                                                                    |           |           | 5.125%          |         |           |          |          |          |          |            |   |   |   |   |   |   | 5.125% |   | 5.125% | 5.125% |   |   |   |   |   |   |   |   |
| Senior Notes; Due 2020 [Member] | Senior Notes [Member]                                                    |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| **Debt Instrument [Line Items]**                                                                           |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Redemption price, (percent)                                                                                |           |           |            |         |           |          | 104.063%      |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Repayments made on debt                                                                                    |           |           |            |         |           |          | $ 302,000,000 |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Debt redeemed                                                                                              |           |           |            |         |           |          | $ 290,000,000 |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| 2.00% Convertible Senior Subordinated Notes due 2043 [Member] | Senior Subordinated Notes [Member]         |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| **Debt Instrument [Line Items]**                                                                           |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Redemption price, (percent)                                                                                |           |           |            |         |           |          |          |          |          |            |   | 100.00% |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Aggregate principal amount                                                                                 |           |           |            |         |           |          |          |          |          |            |   | $ 320,000,000 |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Debt instrument maturity date                                                                              |           |           |            |         |           |          |          |          |          |            |   | Dec.  01,  2043 |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Effective interest rate (percent)                                                                          |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   | 6.00% |   |   |
| Debt instrument interest rate (percent)                                                                    |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   | 2.00% |   | 2.00% | 2.00% |   |   |   |   |   | 2.00% |   |   |
| Contingent principal and interest arrangement                                                              |           |           |            |         |           |          |          |          |          |            |   | Beginning with the six-month period starting December 1, 2018, contingent interest is payable, in addition to regular interest, if the trading price of the Convertible Notes for each of the five trading days ending two trading days prior to any six-month contingent interest period is equal to or greater than $1,200. The amount of contingent interest payable per $1,000 principal amount of the Convertible Notes in respect of any contingent interest period is equal to 0.25% of the average trading price of the Convertible Notes during the specified measurement period. |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Debt instrument conversion rate                                                                            |           |           |            |         |           |          |          |          |          |            |   | 25.2194 shares per $1,000 principal amount |   |   |   |   |   |   | 26.9106 for each $1,000 principal amount |   |   |   |   |   |   |   |   |   |
| Debt instrument conversion price (dollars per share) | $ / shares                                          |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   | $ 37.16 |   |   |   |   |   |   | $ 39.652 |   |   |
| Number of consecutive trading days                                                                         |           |           |            |         |           |          |          |          |          |            |   | 30 days |   |   |   |   |   |   | 5 days |   |   |   |   |   |   |   |   |   |
| Number of trading days | d                                                                                 |           |           |            |         |           |          |          |          |          |            |   | 20 |   |   |   |   |   |   | 2 |   |   |   |   |   |   |   |   |   |
| Convertible notes trading price | $ / shares                                                               |           |           |            |         |           |          |          |          |          |            |   |   |   |   |   |   |   |   | $ 1,200 |   |   |   |   |   |   |   |   |   |
| Volume weighted-average price per share ratio (percent)                                                    |           |           |            |         |           |          |          |          |          |            |   | 120.00% |   |   |   |   |   |   | 0.25% |   |   |   |   |   |   |   |   |   |

| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
We are restricted from paying common stock dividends, prepaying certain senior notes, and repurchasing preferred and common equity unless (1) we are not in default under the terms of the Credit Agreement and (2) the amount of such payments, when added to the aggregate amount of prior restricted payments (as defined in the Credit Agreement) does not exceed $200 million, which amount is subject to increase by a portion of excess cash flows each fiscal year.
+ References
No definition available.
+ Details**Name:**hls_CreditAgreementRestriction**Namespace Prefix:**hls_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                        |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Max senior secured leverage ratio to permit unlimited restricted payments under credit agreement.
+ References
No definition available.
+ Details**Name:**hls_DebtInstrumentCovenantLeverageRatioMaximum**Namespace Prefix:**hls_**Data Type:**xbrli:pureItemType**Balance Type:**na**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                            |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Maximum leverage ratio in the financial covenants in the company's credit agreement.
+ References
No definition available.
+ Details**Name:**hls_DebtInstrumentCovenantsLeverageRatioMaximum**Namespace Prefix:**hls_**Data Type:**xbrli:pureItemType**Balance Type:**na**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                          |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Par value of debt instrument issued plus or minus a premium or a discount.
+ References
No definition available.
+ Details**Name:**hls_DebtInstrumentIssuePricePercentage**Namespace Prefix:**hls_**Data Type:**num:percentItemType**Balance Type:**na**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                       |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Percentage owed on principal amount outstanding for amounts drawn under the debt instrument.
+ References
No definition available.
+ Details**Name:**hls_DebtInstrumentPeriodicPaymentPercentageofPrincipalOutstanding**Namespace Prefix:**hls_**Data Type:**num:percentItemType**Balance Type:**na**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The number of shares converted in a noncash (or part noncash) transaction. Noncash is defined as transactions during a period that do not result in cash receipts or cash payments in the period. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4332-108586Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4304-108586Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4313-108586
+ Details**Name:**us-gaap_ConversionOfStockSharesConverted1**Namespace Prefix:**us-gaap_**Data Type:**xbrli:sharesItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                 |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Percentage points added to the reference rate to compute the variable rate on the debt instrument.
+ References
No definition available.
+ Details**Name:**us-gaap_DebtInstrumentBasisSpreadOnVariableRate1**Namespace Prefix:**us-gaap_**Data Type:**num:percentItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The price per share of the conversion feature embedded in the debt instrument.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 5 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6928298&loc=SL6031898-161870
+ Details**Name:**us-gaap_DebtInstrumentConvertibleConversionPrice1**Namespace Prefix:**us-gaap_**Data Type:**num:perShareItemType**Balance Type:**na**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                           |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Price of the entity's common stock which would be required to be attained for the conversion feature embedded in the debt instrument to become effective.
+ References
No definition available.
+ Details**Name:**us-gaap_DebtInstrumentConvertibleStockPriceTrigger**Namespace Prefix:**us-gaap_**Data Type:**num:perShareItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Description of the conversion terms of a debt instrument which may include the conversion ratio (including all potential conversion ratios if contingently adjustable), type of debt or equity security into which the debt is convertible, the dollars of debt or the number of shares into which the instrument is convertible (or potentially convertible into), the conversion period, any contingencies associated with the conversion terms, and the existence and amount of a beneficial conversion feature.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21521-112644Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(5)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21506-112644Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21475-112644
+ Details**Name:**us-gaap_DebtInstrumentConvertibleTermsOfConversionFeature**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Threshold period of specified consecutive trading days within which common stock price to conversion price of convertible debt instruments must exceed threshold percentage for a specified number of trading days to trigger conversion feature, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.
+ References
No definition available.
+ Details**Name:**us-gaap_DebtInstrumentConvertibleThresholdConsecutiveTradingDays**Namespace Prefix:**us-gaap_**Data Type:**xbrli:durationItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                          |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Minimum percentage of common stock price to conversion price of convertible debt instruments to determine eligibility of conversion.
+ References
No definition available.
+ Details**Name:**us-gaap_DebtInstrumentConvertibleThresholdPercentageOfStockPriceTrigger**Namespace Prefix:**us-gaap_**Data Type:**num:percentItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Threshold number of specified trading days that common stock price to conversion price of convertible debt instruments must exceed threshold percentage within a specified consecutive trading period to trigger conversion feature.
+ References
No definition available.
+ Details**Name:**us-gaap_DebtInstrumentConvertibleThresholdTradingDays**Namespace Prefix:**us-gaap_**Data Type:**xbrli:integerItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Face (par) amount of debt instrument at time of issuance.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 55 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399
+ Details**Name:**us-gaap_DebtInstrumentFaceAmount**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399
+ Details**Name:**us-gaap_DebtInstrumentInterestRateEffectivePercentage**Namespace Prefix:**us-gaap_**Data Type:**num:percentItemType**Balance Type:**na**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Contractual interest rate for funds borrowed, under the debt agreement.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682
+ Details**Name:**us-gaap_DebtInstrumentInterestRateStatedPercentage**Namespace Prefix:**us-gaap_**Data Type:**num:percentItemType**Balance Type:**na**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                                               |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.
+ References
No definition available.
+ Details**Name:**us-gaap_DebtInstrumentLineItems**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(2)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682
+ Details**Name:**us-gaap_DebtInstrumentMaturityDate**Namespace Prefix:**us-gaap_**Data Type:**xbrli:dateItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Percentage price of original principal amount of debt at which debt can be redeemed by the issuer.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 470 -Section 50 -Paragraph 3 -Subparagraph e -URI http://asc.fasb.org/extlink&oid=6479336&loc=d3e64711-112823
+ Details**Name:**us-gaap_DebtInstrumentRedemptionPricePercentage**Namespace Prefix:**us-gaap_**Data Type:**num:percentItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                      |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Face (par) amount of the original debt instrument that was repurchased.
+ References
No definition available.
+ Details**Name:**us-gaap_DebtInstrumentRepurchasedFaceAmount**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**instant |
| X                                                                                                                                                                                                                                                         |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Gross amount of debt extinguished.
+ References
No definition available.
+ Details**Name:**us-gaap_ExtinguishmentOfDebtAmount**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 50 -Section 40 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=49170532&loc=d3e12317-112629Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3602-108585Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 50 -Section 40 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=49170532&loc=d3e12355-112629
+ Details**Name:**us-gaap_GainsLossesOnExtinguishmentOfDebt**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                        |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.
+ References
No definition available.
+ Details**Name:**us-gaap_LettersOfCreditOutstandingAmount**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(16)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(16)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878
+ Details**Name:**us-gaap_LineOfCredit**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                      |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The fee, expressed as a percentage of the line of credit facility, for the line of credit facility regardless of whether the facility has been used.
+ References
No definition available.
+ Details**Name:**us-gaap_LineOfCreditFacilityCommitmentFeePercentage**Namespace Prefix:**us-gaap_**Data Type:**num:percentItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The effective interest rate at the end of the reporting period.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(b),22(b)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682
+ Details**Name:**us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd**Namespace Prefix:**us-gaap_**Data Type:**num:percentItemType**Balance Type:**na**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(b),22(b)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682
+ Details**Name:**us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(b),22(b)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682
+ Details**Name:**us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Description of conditions, facts and circumstances that would trigger a payment of principal or interest which was not otherwise immediately due and payable.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(3)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21475-112644
+ Details**Name:**us-gaap_LongTermDebtContingentPaymentOfPrincipalOrInterest**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                      |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The percentage rate used to calculate dividend payments on preferred stock.
+ References
No definition available.
+ Details**Name:**us-gaap_PreferredStockDividendRatePercentage**Namespace Prefix:**us-gaap_**Data Type:**num:percentItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                            |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The cash inflow during the period from additional borrowings in aggregate debt. Includes proceeds from short-term and long-term debt.
+ References
No definition available.
+ Details**Name:**us-gaap_ProceedsFromIssuanceOfDebt**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of cash inflow from contractual arrangement with the lender, including but not limited to, letter of credit, standby letter of credit and revolving credit arrangements.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Financing Activities -URI http://asc.fasb.org/extlink&oid=6513228Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 14 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3255-108585Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(f)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690
+ Details**Name:**us-gaap_ProceedsFromLinesOfCredit**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The cash outflow for debt initially having maturity due after one year or beyond the normal operating cycle, if longer.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 15 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3291-108585Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Financing Activities -URI http://asc.fasb.org/extlink&oid=6513228
+ Details**Name:**us-gaap_RepaymentsOfLongTermDebt**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**duration |
| X                                                                                                                                                          |
|------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_LongtermDebtTypeAxis=us-gaap_CapitalLeaseObligationsMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                               |
|---------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_RangeAxis=us-gaap_MinimumMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                               |
|---------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_RangeAxis=us-gaap_MaximumMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                              |
|------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_LongtermDebtTypeAxis=us-gaap_SeniorNotesMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                 |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_StatementClassOfStockAxis=us-gaap_ConvertiblePreferredStockMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                        |
|----------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                    |
|------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_DebtInstrumentAxis=hls_SeniorNotes05.75Due2025Member**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                               |
|-------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_DebtInstrumentAxis=hls_TheCreditAgreementMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                               |
|-------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_LongtermDebtTypeAxis=us-gaap_LoansPayableMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                            |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_VariableRateAxis=us-gaap_FederalFundsEffectiveSwapRateMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                              |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                    |
|------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_StatementScenarioAxis=us-gaap_ScenarioForecastMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                               |
|-------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_CreditFacilityAxis=us-gaap_LetterOfCreditMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_DebtInstrumentAxis=hls_A2014CreditAgreementMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                              |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_DebtInstrumentAxis=hls_A7.25and7.75SeniorNotesdue2018and2022RespectivelyMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                   |
|-----------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_DebtInstrumentAxis=hls_SeniorNotes7.25Due2018Member**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                   |
|-----------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_DebtInstrumentAxis=hls_SeniorNotes0575Due2024Member**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                   |
|-----------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_DebtInstrumentAxis=hls_SeniorNotes7.75Due2022Member**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                     |
|-------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_DebtInstrumentAxis=hls_SeniorNotes05.125Due2023Member**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                               |
|-------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_DebtInstrumentAxis=hls_SeniorNotesDue2020Member**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                           |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_DebtInstrumentAxis=hls_A2.00ConvertibleSeniorSubordinatedNotesdue2043Member**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                          |
|------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_LongtermDebtTypeAxis=us-gaap_SeniorSubordinatedNotesMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |