Income Taxes - Summary of Effective Tax Rates (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended						1 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2012 Minimum [Member]	Dec. 31, 2012 Maximum [Member]
Income Tax Expense (Benefit), Continuing Operations, Income Tax Reconciliation [Abstract]
Tax benefit at the U.S. federal statutory income tax rate	$ (1,334)		$ (1,315)		$ (1,401)
State and local taxes, net of Federal benefit	(21)		2		3
Validation of tax accounts	(16)	[1]	16	[1]	(20)	[1]
Change in tax rate used to value deferred taxes	(7)		0		0
Change in valuation allowance reserves	27	[2]	(133)	[2]	(8)	[2]
Change in uncertain tax position reserves	(15)	[3]	(14)	[3]	(22)	[3]
Other	(40)	[4]	13	[4]	(5)	[4]
Total income tax expense (benefit)	$ (1,406)		$ (1,431)		$ (1,453)
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation [Abstract]
Tax benefit at the U.S. federal statutory income tax rate, percent	(35.00%)		(35.00%)		(35.00%)
State and local taxes, net of Federal benefit, percent	(0.60%)		0.10%		0.10%
Validation of tax accounts, percent	(0.40%)	[1]	0.40%	[1]	(0.50%)	[1]
Change in tax rate used to value deferred taxes, percent	(0.20%)		0.00%		0.00%
Change in valuation allowance reserves, percent	0.70%	[2]	(3.50%)	[2]	(0.20%)	[2]
Change in uncertain tax position reserves, percent	(0.40%)	[3]	(0.40%)	[3]	(0.60%)	[3]
Other, percent	(1.00%)	[4]	0.30%	[4]	(0.10%)	[4]
Total income tax benefit, percent	(36.90%)		(38.10%)		(36.30%)
Net Operating Loss Carryforward Period							15 years	20 years

[1] For 2012, the amount relates to corrections to the current tax liability account and to deferred tax prior period adjustments. For 2011 and 2010, the amounts relate to deferred tax prior period adjustments.

[2] For 2012, the amount relates to increase in valuation allowance on states with net operating loss carryforward periods of 15 to 20 years. For 2011, the amount relates mainly to the release of a valuation allowance previously established on foreign tax credits.

[3] For 2012, 2011 and 2010, the amounts primarily relate to the conclusion of state audits and expiration of state statutes of limitations.

[4] For 2012, the amount primarily relates to a reclassification of deferred tax accounts between continuing operations and discontinued operations with no consolidated impact. For 2011, the amounts primarily relate to the non-deductible portion of an accrual related to mortgage servicing matters. For 2010, the amounts relates to the amortization of purchase accounting adjustments on leveraged leases.