|**Fair Value Measurements (Tables)**                                          | 12 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
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|**Fair Value Disclosures [Abstract]**                                         |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis    | Our financial assets and liabilities that are measured at fair value on a recurring basis are as follows (in millions):Fair Value Measurements at Reporting Date UsingAs of December 31, 2011Fair ValueQuoted Prices in Active Markets for Identical Assets(Level 1)Significant Other Observable Inputs(Level 2)Significant Unobservable Inputs(Level 3)Valuation Technique(1)Current portion of restricted marketable securities$15.0$—$15.0$—MOther long-term assets:Restricted marketable securities30.2—30.2—MAs of December 31, 2010Current portion of restricted marketable securities$18.2$—$18.2$—MPrepaid expenses and other current assets:June 2009 trading swap1.2—1.2—IOther long-term assets:Restricted marketable securities19.3—19.3—MOther current liabilities:March 2006 trading swap(12.1)—(12.1)—I
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|As of December 31, 2011                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|Current portion of restricted marketable securities                           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|Other long-term assets:                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|Restricted marketable securities                                              |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|As of December 31, 2010                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|Current portion of restricted marketable securities                           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|Prepaid expenses and other current assets:                                    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|June 2009 trading swap                                                        |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|Other long-term assets:                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|Restricted marketable securities                                              |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|Other current liabilities:                                                    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|March 2006 trading swap                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|Schedule of Fair Value, Assets Measured on Nonrecurring Basis                 | Assets measured at fair value on a nonrecurring basis are as follows (in millions):Fair Value Measurements at ReportingDate UsingTotal LossesNet Carrying Value as of December 31,2009Quoted Prices inActive Marketsfor IdenticalAssets(Level 1)SignificantOtherObservableInputs(Level 2)SignificantUnobservableInputs(Level 3)Year Ended December 31,2009Investments in and advances to nonconsolidated affiliates$1.7$—$—$1.7$0.3Other long-term assets:Assets held for sale14.2—14.2—0.9                                                                                                                                                                                                                                                                                                                           
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|                                                                              | Net Carrying Value as of December 31,2009                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             
|Investments in and advances to nonconsolidated affiliates                     | $                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     
|Other long-term assets:                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|Assets held for sale                                                          | 14.2                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  
|Schedule of Carrying Amounts and Estimated Fair Values, Financial Instruments | The carrying amounts and estimated fair values for all of our other financial instruments are presented in the following table (in millions):As of December 31, 2011As of December 31, 2010Carrying AmountEstimated Fair ValueCarrying AmountEstimated Fair ValueInterest rate swap agreements:March 2006 trading swap$—$—$(12.1)$(12.1)June 2009 trading swap——1.21.2Long-term debt:Advances under $500 million revolving credit facility110.0110.078.078.0Term loan facility97.597.5——10.75% Senior Notes due 2016——495.5543.27.25% Senior Notes due 2018336.7330.0275.0280.58.125% Senior Notes due 2020285.8290.0285.5311.87.75% Senior Notes due 2022312.0301.1250.0258.1Other bonds payable1.51.51.81.8Other notes payable35.335.336.436.4Financial commitments:Letters of credit—44.6—45.6                     
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|                                                                              | As of December 31, 2011                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               
|                                                                              | Carrying Amount                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|Interest rate swap agreements:                                                |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|March 2006 trading swap                                                       | $                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     
|June 2009 trading swap                                                        | —                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     
|Long-term debt:                                                               |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|Advances under $500 million revolving credit facility                         | 110.0                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 
|Term loan facility                                                            | 97.5                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  
|10.75% Senior Notes due 2016                                                  | —                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     
|7.25% Senior Notes due 2018                                                   | 336.7                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 
|8.125% Senior Notes due 2020                                                  | 285.8                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 
|7.75% Senior Notes due 2022                                                   | 312.0                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 
|Other bonds payable                                                           | 1.5                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   
|Other notes payable                                                           | 35.3                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  
|Financial commitments:                                                        |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|Letters of credit                                                             | —                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     

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