Condensed Consolidating Financial Data (Condensed Consolidating Balance Sheets) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Condensed Financial Statements, Captions [Line Items]
Current assets	$ 3,394.0	$ 3,493.5
Investment in subsidiaries
Non-current assets	3,624.1	3,623.2
Total assets	7,018.1	7,116.7
Current liabilities	1,654.8	1,463.7
Non-current liabilities	3,802.5	3,741.0
Stockholders' equity	1,560.8	1,912.0
Total liabilities and stockholders' equity	7,018.1	7,116.7
Parent [Member]
Condensed Financial Statements, Captions [Line Items]
Current assets	69.1	359.0
Investment in subsidiaries	5,589.0	5,688.8
Non-current assets	117.6	114.5
Total assets	5,775.7	6,162.3
Current liabilities	184.1	260.8
Non-current liabilities	4,030.8	3,989.5
Stockholders' equity	1,560.8	1,912.0
Total liabilities and stockholders' equity	5,775.7	6,162.3
Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Current assets	940.7	995.9
Investment in subsidiaries	1,610.8	1,748.1
Non-current assets	3,979.5	4,003.9
Total assets	6,531.0	6,747.9
Current liabilities	539.8	589.0
Non-current liabilities	745.1	507.0
Stockholders' equity	5,246.1	5,651.9
Total liabilities and stockholders' equity	6,531.0	6,747.9
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Current assets	2,382.1	2,140.0
Investment in subsidiaries
Non-current assets	892.1	914.0
Total assets	3,274.2	3,054.0
Current liabilities	930.9	614.1
Non-current liabilities	389.6	654.9
Stockholders' equity	1,953.7	1,785.0
Total liabilities and stockholders' equity	3,274.2	3,054.0
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Current assets	2.1	(1.4)
Investment in subsidiaries	(7,199.8)	(7,436.9)
Non-current assets	(1,365.1)	(1,409.2)
Total assets	(8,562.8)	(8,847.5)
Current liabilities		(0.2)
Non-current liabilities	(1,363.0)	(1,410.4)
Stockholders' equity	(7,199.8)	(7,436.9)
Total liabilities and stockholders' equity	$ (8,562.8)	$ (8,847.5)