Income Taxes - Net Deferred Tax Position (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013
Deferred Tax Assets:
Credit loss reserves	$ 881		$ 1,220
Federal and state unused tax benefit carryforwards	1,335		1,080
Market value adjustment related to derivatives and long-term debt carried at fair value	449		392
Interests in Real Estate Mortgage Investment Conduits	326	[1]	394	[1]
Accrued expenses not currently deductible	191		199
Other	280		372
Total deferred tax assets	3,462		3,657
Valuation allowance	(878)		(931)
Total deferred tax assets net of valuation allowance	2,584		2,726
Deferred Tax Liabilities:
Fee income	74		82
Other	66		64
Total deferred tax liabilities	140		146
Net deferred tax assets	$ 2,444		$ 2,580

[1] Real Estate Mortgage Investment Conduits ("REMIC") are investment vehicles that hold commercial and residential mortgages in trust and issue securities representing an undivided interest in these mortgages. We hold portfolios of noneconomic residual interests in a number of REMICs through one of our subsidiaries. This item represents the tax basis in such interests which has accumulated as a result of tax rules requiring the recognition of income related to such noneconomic residuals.