Income Taxes - Additional Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014		Mar. 31, 2013
Income Taxes Other Information [Line Items]
Income Tax Expense (Benefit)	$ 125	[1]	$ 161	[1]
Effective Income Tax Rate Reconciliation, Percent	24.00%		31.00%
Unrecognized Tax Benefits	271
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	$ 180

[1] Amortization expense related to qualified affordable housing investment costs is recognized in provision for income taxes for each of the periods presented as allowed by a recently adopted accounting standard. Prior to the first quarter of 2014, these amounts were recognized in other noninterest expense.