| **Cash and Marketable Securities - Components of Investments (Details) - USD ($) $ in Millions** | Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 |
|--------------------------------------------------------------------------------------------------|---------------|---------------|---------------|---------------|
| **Cash and Cash Equivalents [Line Items]**                                                       |          |          |          |          |
| Cash & Cash Equivalents                                                                      | $ 40.5        | $ 61.6        | $ 66.7        | $ 64.5        |
| Total restricted cash                                                                            | 60.9          | 45.9          |          |          |
| Restricted Marketable Securities                                                                 | 57.7          | 56.2          |          |          |
| Total                                                                                            | 159.1         | 163.7         |          |          |
| Cash [Member]                                                                                    |          |          |          |          |
| **Cash and Cash Equivalents [Line Items]**                                                       |          |          |          |          |
| Cash & Cash Equivalents                                                                      | 40.5          | 61.6          |          |          |
| Total restricted cash                                                                            | 60.9          | 45.9          |          |          |
| Restricted Marketable Securities                                                                 | 0.0           | 0.0           |          |          |
| Total                                                                                            | 101.4         | 107.5         |          |          |
| Equity Securities [Member]                                                                       |          |          |          |          |
| **Cash and Cash Equivalents [Line Items]**                                                       |          |          |          |          |
| Cash & Cash Equivalents                                                                      | 0.0           | 0.0           |          |          |
| Total restricted cash                                                                            | 0.0           | 0.0           |          |          |
| Restricted Marketable Securities                                                                 | 57.7          | 56.2          |          |          |
| Total                                                                                            | $ 57.7        | $ 56.2        |          |          |

| X                                                                                                                                                                                                                                                                                                                                       |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Total investments of the Company which includes cash, cash equivalents, restricted cash, and marketable securities.
+ References
No definition available.
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|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.
+ References
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| 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.
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Total debt and equity financial instruments including: (1) securities held-to-maturity, (2) trading securities, and (3) securities available-for-sale that are pledged to one or more secured parties who have the right to buy, sell, or re-pledge the collateral.
+ References
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|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The carrying amounts of cash and cash equivalent items which are restricted as to withdrawal or usage. Restrictions may include legally restricted deposits held as compensating balances against short-term borrowing arrangements, contracts entered into with others, or entity statements of intention with regard to particular deposits; however, time deposits and short-term certificates of deposit are not generally included in legally restricted deposits. Excludes compensating balance arrangements that are not agreements which legally restrict the use of cash amounts shown on the balance sheet. For a classified balance sheet represents the current portion only (the noncurrent portion has a separate concept); there is a separate and distinct element for unclassified presentations.
+ References
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| X                                                                                                                                     |
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| X                                                                                                                                                 |
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