Accumulated Other Comprehensive Income (Loss) - Summary of Changes in Accumulated Other Comprehensive Income (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012		Dec. 31, 2012
Unrealized gains (losses) on cash flow hedging instruments:
Balance at beginning of period	$ (358)		$ (494)
Net gains arising during period, net of tax of $20 million and $29 million, respectively	36		50
Reclassification adjustment for losses realized in net income, net of tax of $73 million and $3 million, respectively	132		5
Total other comprehensive income (loss) for period	168		55
Balance at end of period	(190)		(439)
Unrealized gains (losses) on securities available-for-sale, not other-than temporarily impaired:
Balance at beginning of period	115		102
Net unrealized holding gains arising during period, net of tax of $- million and $(5) million, respectively	0		(8)
Reclassification adjustment for gains realized in net income, net of tax of $(62) million and $- million, respectively(1)	(115)	[1]	(1)	[1]
Total other comprehensive loss for period	(115)		(9)
Balance at end of period	0		93
Unrealized gains (losses) on other-than-temporarily impaired debt securities available-for-sale:
Balance at beginning of period	1		0
Other-than-temporary impairment on debt securities available-for-sale recognized in other comprehensive income, net of tax of $- million and $- million, respectively	0		0
Reclassification adjustment for gains realized in net income, net of tax of $(1) million and $- million, respectively(1)	(1)	[1]	0	[1]
Total other comprehensive loss for period	(1)		0
Balance at end of period	0		0
Pension and postretirement benefit plan liability:
Balance at beginning and end of period	(26)		(11)
Total other comprehensive income for period	0		0
Balance at end of period	(26)		(11)
Foreign currency translation adjustments:
Balance at beginning of period	11		7
Translation gains (losses), net of tax of $(1) million and $1 million, respectively	(5)		5
Reclassification adjustment for gains realized in net income, net of tax of $(9) million and $- million, respectively	(15)	[1]	0	[1]
Total other comprehensive income (loss) for period	(20)		5
Balance at end of period	(9)		12
Total accumulated other comprehensive loss at end of period	$ (225)		$ (345)		$ (257)

[1] The amount reclassified for the three months ended March 31, 2013 is included in income (loss) from discontinued operations in our consolidated statement of income (loss).