Significant Accounting Policies Significant Accounting Policies - additional information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other Noninterest Expense	$ 99	[1]	$ 153	[1]	$ 376	[1]	$ 402	[1]
New Accounting Pronouncement, Early Adoption, Effect [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other Depreciation and Amortization			13				33
provision for income taxes [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other Depreciation and Amortization	$ 14		$ 13		$ 41		$ 33

[1] Amortization expense related to qualified affordable housing investment costs is recognized in provision/(benefit) 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.