| **Accounts Receivable (Tables)**                                | 12 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
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| **Receivables [Abstract]**                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
| Schedule of Accounts Receivable                                 | Accounts receivable consists of the following (in millions): As of December 31, 2016 2015Current:   Patient accounts receivable, net of allowance for doubtful accounts of $53.9 million in 2016; $39.3 million in 2015$432.0 $403.3Other accounts receivable11.8 7.2 443.8 410.5Noncurrent patient accounts receivable, net of allowance for doubtful accounts of $49.5 million in 2016; $32.3 million in 2015125.9 96.6Accounts receivable, net$569.7 $507.1 |
| Schedule of Activity Related to Allowance for Doubtful Accounts | The following is the activity related to our allowance for doubtful accounts (in millions):For the Year Ended December 31, Balance at Beginning of Period Additions and Charges to Expense Deductions and Accounts Written Off Balance at End of Period2016 $71.6 $61.2 $(29.4) $103.42015 $43.0 $47.2 $(18.6) $71.62014 $33.1 $31.6 $(21.7) $43.0                                                                                         |

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| - Definition
Tabular disclosure of financing receivables (examples of financing receivables include loans, trade accounts receivable and notes receivable) and activity in the allowance for credit losses account.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 11B -URI http://asc.fasb.org/extlink&oid=66008989&loc=SL6953423-111524
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| - References
No definition available.
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| - Definition
Tabular disclosure of the various types of trade accounts and notes receivable and for each the gross carrying value, allowance, and net carrying value as of the balance sheet date. Presentation is categorized by current, noncurrent and unclassified receivables.
+ 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 210.5-02.3,4) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682
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