Income Taxes Components of Income Tax Provision (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Components of income tax provision [Line Items]
Current Federal Tax Expense (Benefit)	$ 365		$ (158)		$ 592
Current State and Local Tax Expense (Benefit)	29		(15)		26
Current Income Tax Expense (Benefit)	394		(173)		618
Deferred Federal Income Tax Expense (Benefit)	99		444		229
Deferred State and Local Income Tax Expense (Benefit)	0		51		(35)
Deferred Income Tax Expense (Benefit)	99		495		194
Income Tax Expense (Benefit)	$ 493	[1]	$ 322	[1]	$ 812	[1]

[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 an accounting standard adopted in 2014. Prior to 2014, these amounts were recognized in other noninterest expense.