Income Taxes - Summary of Effective Tax Rates (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Income Taxes [Line Items]
Tax expense (benefit) at the U.S. Federal statutory income tax rate	$ (101)	$ (708)	$ (1,237)	$ (1,011)
State and local taxes, net of Federal benefit	7	1	(5)	1
Adjustment to current liability account	(6)		(37)
Change in tax rate used to value deferred taxes			(7)
Change in valuation allowance reserves	5	(3)	16	(144)
Deferred tax validation	8	9	(34)	12
Change in uncertain tax position reserves	(12)	28	(19)	(2)
Foreign tax credits		(12)		(12)
Other	1	(4)	(2)	(5)
Total income tax expense (benefit)	$ (98)	$ (689)	$ (1,325)	$ (1,161)
Tax expense (benefit) at the U.S. Federal statutory income tax rate	(35.00%)	(35.00%)	(35.00%)	(35.00%)
State and local taxes, net of Federal benefit	2.40%		0.10%
Adjustment to current liability account	2.00%		(1.00%)
Change in tax rate used to value deferred taxes			(0.20%)
Change in valuation allowance reserves	1.70%	(0.10%)	0.40%	(5.00%)
Deferred tax validation	2.80%	0.40%	(1.00%)	0.40%
Change in uncertain tax position reserves	(4.10%)	1.40%	(0.50%)	(0.10%)
Foreign tax credits		(0.60%)		(0.40%)
Other	0.40%	(0.10%)	(0.10%)	(0.10%)
Total income tax expense (benefit)	(33.80%)	(34.00%)	(37.50%)	(40.20%)