Other Comprehensive Loss - Components of Accumulated Other Comprehensive Loss (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Accumulated Other Comprehensive Income Loss [Line Items]
Change in fair value of derivative instruments, beginning balance	$ (253)	$ (272)	$ (355)
Change in fair value of derivative instruments net of income tax benefit	(96)	(197)	(161)
Change in fair value of derivatives instruments, (income) expense reclassified into operations from other comprehensive income	78	216	244
Change in fair value of derivatives instruments, ending balance	(271)	(253)	(272)
Defined benefit plans, beginning balance	(169)	(143)	(106)
Defined benefit plans	(56)	(42)	(48)
Defined benefit plans, (income) expense reclassified into operations from other comprehensive income	29	16	11
Defined benefit plans, ending balance	(196)	(169)	(143)
Foreign currency translation adjustments, beginning balance	(25)	(19)	(3)
Foreign currency translation adjustments	24	(6)	(16)
Foreign currency translation adjustments, ending balance	(1)	(25)	(19)
Unrealized gain on available-for-sale securities, beginning balance	7	6	14
Unrealized gains on available-for-sale securities	4	1	1
Unrealized gains on available-for-sale securities, (income) expense reclassified into operations from other comprehensive income			(9)
Unrealized gain on available-for-sale securities, ending balance	11	7	6
Accumulated other comprehensive income (loss), net of tax, beginning balance	(440)	(428)	(450)
Unrealized gains on available-for-sale securities	4	1	1
Foreign currency translation adjustments	24	(6)	(16)
Defined benefit plans	(56)	(42)	(48)
Change in fair value of derivative instruments, net of income tax benefit	(96)	(197)	(161)
Expense reclassified into operations from other comprehensive income, Total	107	232	246
Accumulated other comprehensive income (loss), net of tax, Ending balance	$ (457)	$ (440)	$ (428)