Income Taxes - Net Deferred Tax Position (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Deferred Tax Assets:
Credit loss reserves	$ 1,678	$ 2,204
Receivables held for sale	921	0
Unused tax benefit carryforwards	930	762
Market value adjustment related to derivatives and long-term debt carried at fair value	624	446
Real Estate Mortgage Investment Conduit (“REMIC”)	505	226
Other	463	577
Total deferred tax assets	5,121	4,215
Valuation allowance	982	662
Total deferred tax assets net of valuation allowance	4,139	3,553
Deferred Tax Liabilities:
Fee income	105	128
Other	145	111
Total deferred tax liabilities	250	239
Net deferred tax assets	3,889	3,314
Valuation Allowance [Abstract]
State tax benefit loss limitations	926	606
Deferred capital loss on sale to affiliates	49	49
Other	$ 7	$ 7