Condensed Consolidating Balance Sheets (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Current assets	$ 3,972.1	$ 3,493.5
Non-current assets	3,762.3	3,623.2
Total assets	7,734.4	7,116.7
Current liabilities	1,806.8	1,463.7
Non-current liabilities	4,230.9	3,741.0
Stockholders' equity	1,696.7	1,912.0
Total liabilities and stockholders' equity	7,734.4	7,116.7
Parent Company
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Current assets	508.9	359.0
Investment in subsidiaries	6,020.7	5,688.8
Non-current assets	2,074.4	114.5
Total assets	8,604.0	6,162.3
Current liabilities	267.8	260.8
Non-current liabilities	6,639.5	3,989.5
Stockholders' equity	1,696.7	1,912.0
Total liabilities and stockholders' equity	8,604.0	6,162.3
Guarantor Subsidiaries
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Current assets	1,047.5	995.9
Investment in subsidiaries	1,832.5	1,748.1
Non-current assets	5,622.6	4,003.9
Total assets	8,502.6	6,747.9
Current liabilities	576.3	589.0
Non-current liabilities	2,199.3	507.0
Stockholders' equity	5,727.0	5,651.9
Total liabilities and stockholders' equity	8,502.6	6,747.9
Non-Guarantor Subsidiaries
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Current assets	2,415.7	2,140.0
Non-current assets	3,647.7	914.0
Total assets	6,063.4	3,054.0
Current liabilities	962.7	614.1
Non-current liabilities	2,974.5	654.9
Stockholders' equity	2,126.2	1,785.0
Total liabilities and stockholders' equity	6,063.4	3,054.0
Consolidation, Eliminations
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Current assets		(1.4)
Investment in subsidiaries	(7,853.2)	(7,436.9)
Non-current assets	(7,582.4)	(1,409.2)
Total assets	(15,435.6)	(8,847.5)
Current liabilities		(0.2)
Non-current liabilities	(7,582.4)	(1,410.4)
Stockholders' equity	(7,853.2)	(7,436.9)
Total liabilities and stockholders' equity	$ (15,435.6)	$ (8,847.5)