v2.4.0.6
Summary of Significant Accounting Policies (Unrecognized Tax Benefits) (Details) (USD $)
In Millions, unless otherwise specified
 3 Months Ended 12 Months Ended
Mar. 31, 2013
Dec. 31, 2012
Income Tax Contingency [Line Items]    
Unrecognized Tax Benefits $ 22.0 $ 38.4
Income Tax Penalties and Interest Accrued 9.0 12.4
Decreases in Unrecognized Tax Benefits Resulting from Settlements with Taxing Authorities, Portion Which Affected Effective Tax Rate 0.9  
Interest Expense Resulting from Income Tax Examination 4.9 3.8
Decreases in Unrecognized Tax Benefits Resulting from Settlements with Taxing Authorities 16.7  
Income Tax Expense (Benefit) Resulting from Income Tax Examination Settlement 3.2  
Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Amount of Unrecorded Benefit 10.1  
Significant Change in Unrecognized Tax Benefits is Reasonably Possible that Would Impact Effective Tax Rate 8.0  
Internal Revenue Service (IRS)
    
Income Tax Contingency [Line Items]    
Unrecognized Tax Benefits that Would Impact Effective Tax Rate   19.9
Decreases in Unrecognized Tax Benefits Resulting from Settlements with Taxing Authorities, Portion Which Affected Effective Tax Rate 0.1  
Decreases in Unrecognized Tax Benefits Resulting from Settlements with Taxing Authorities $ 20.8