Supplemental Cash Flow Information - Supplemental Cash Flow Reconciliation (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Supplemental Cash Flow Information [Abstract]
Interest expense, net of interest capitalized	$ 2,101.3	[1]	$ 2,122.3	[1]	$ 1,981.6	[1]
Adjustments to reconcile to cash paid for interest:
Net change in accurals	(14.1)		(12.5)		(12.8)
Amortization of deferred finance charges	(88.5)		(70.3)		(76.4)
Net amortization of discounts and premiums	(226.3)		(157.2)		(163.7)
Reclassification of accumulated other comprehensive loss	0		(183.2)		0
Amortization of other comprehensive loss	(29.1)		(83.3)		(36.3)
Rollover of PIK interest to principal	(1.0)		(1.1)		(1.0)
Change in fair value of derivative instruments	29.6		70.3		74.7
Cash paid for interest	1,771.9		1,685.0		1,766.1
Cash payments (refunds) of income taxes, net	$ 16.5	[2]	$ 5.4	[2]	$ (190.2)	[2]

[1] Interest capitalized in 2012, 2011, and 2010 was $38.2 million, $22.8 million, and $1.4 million, respectively.

[2] The 2010 net receipt includes $220.8 million of federal income tax refund received, offset by other federal, state, and foreign taxes paid during the year.