| **Fair Value Measurements - Table 1 (Details) - USD ($) $ in Millions**                                            | 3 Months Ended | 6 Months Ended |
|--------------------------------------------------------------------------------------------------------------------|----------------|----------------|
||
| **Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]**                                      |           |           |
| Redeemable Noncontrolling Interest, Fair Value                                                                     | $ 121.1        | $ 120.0        |
| Fair Value, Inputs, Level 1 [Member]                                                                               |           |           |
| **Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]**                                      |           |           |
| Redeemable Noncontrolling Interest, Fair Value                                                                     | 0.0            | 0.0            |
| Fair Value, Inputs, Level 2 [Member]                                                                               |           |           |
| **Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]**                                      |           |           |
| Redeemable Noncontrolling Interest, Fair Value                                                                     | 0.0            | 0.0            |
| Fair Value, Inputs, Level 3 [Member]                                                                               |           |           |
| **Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]**                                      |           |           |
| Redeemable Noncontrolling Interest, Fair Value                                                                     | 121.1          | 120.0          |
| Other Current Assets [Member] | Restricted Marketable Securities [Member]                                          |           |           |
| **Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]**                                      |           |           |
| Marketable Securities, Fair Value                                                                                  | $ 16.1         | $ 27.4         |
| Fair Value Measurements, Valuation Techniques                                                                      | M              | M              |
| Other Current Assets [Member] | Restricted Marketable Securities [Member] | Fair Value, Inputs, Level 1 [Member]   |           |           |
| **Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]**                                      |           |           |
| Marketable Securities, Fair Value                                                                                  | $ 0.0          | $ 0.0          |
| Other Current Assets [Member] | Restricted Marketable Securities [Member] | Fair Value, Inputs, Level 2 [Member]   |           |           |
| **Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]**                                      |           |           |
| Marketable Securities, Fair Value                                                                                  | 16.1           | 27.4           |
| Other Current Assets [Member] | Restricted Marketable Securities [Member] | Fair Value, Inputs, Level 3 [Member]   |           |           |
| **Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]**                                      |           |           |
| Marketable Securities, Fair Value                                                                                  | 0.0            | 0.0            |
| Other Long-term Assets [Member] | Restricted Marketable Securities [Member]                                        |           |           |
| **Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]**                                      |           |           |
| Marketable Securities, Fair Value                                                                                  | $ 40.1         | $ 29.9         |
| Fair Value Measurements, Valuation Techniques                                                                      | M              | M              |
| Other Long-term Assets [Member] | Restricted Marketable Securities [Member] | Fair Value, Inputs, Level 1 [Member] |           |           |
| **Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]**                                      |           |           |
| Marketable Securities, Fair Value                                                                                  | $ 0.0          | $ 0.0          |
| Other Long-term Assets [Member] | Restricted Marketable Securities [Member] | Fair Value, Inputs, Level 2 [Member] |           |           |
| **Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]**                                      |           |           |
| Marketable Securities, Fair Value                                                                                  | 40.1           | 29.9           |
| Other Long-term Assets [Member] | Restricted Marketable Securities [Member] | Fair Value, Inputs, Level 3 [Member] |           |           |
| **Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]**                                      |           |           |
| Marketable Securities, Fair Value                                                                                  | $ 0.0          | $ 0.0          |
| Redeemable Noncontrolling Interest [Member]                                                                        |           |           |
| **Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]**                                      |           |           |
| Fair Value Measurements, Valuation Techniques                                                                      | I              | I              |

| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.
+ References
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|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Description of the inputs and valuation technique(s) used to measure fair value.
+ References
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|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The aggregate fair value as of the reporting date of all noncontrolling interests which are redeemable by the (parent) entity (1) at a fixed or determinable price on a fixed or determinable date, (2) at the option of the holder of the noncontrolling interest, or (3) upon occurrence of an event that is not solely within the control of the (parent) entity. This item includes noncontrolling interest holder's ownership (or holders' ownership) regardless of the type of equity interest (common, preferred, other) including all potential organizational (legal) forms of the investee entity.
+ References
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