CONSOLIDATED STATEMENT OF CHANGES IN SHAREHOLDERS' EQUITY (UNAUDITED) (USD $) In Millions, unless otherwise specified	Total	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income [Member]
Balance at beginning of period at Dec. 31, 2012		$ 1,565
Balance at beginning of period at Dec. 31, 2012			0	14,123	1,363	785
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Employee benefit plans				(12)
Net income	367
Cash dividends declared on preferred stock					(55)
Adjustment to add other-than-temporary impairment on securities held-to-maturity due to the consolidation of a variable interest entity	(67)					(67)
Other comprehensive income (loss), net of tax	(687)					(687)
Balance at end of period at Sep. 30, 2013	17,382	1,565
Balance at end of period at Sep. 30, 2013	15,817		0	14,111	1,675	31
Balance at beginning of period at Dec. 31, 2013	16,464	1,565
Balance at beginning of period at Dec. 31, 2013	14,899		0	14,106	952	(159)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Employee benefit plans				3
Net income	284
Cash dividends declared on preferred stock					(55)
Adjustment to add other-than-temporary impairment on securities held-to-maturity due to the consolidation of a variable interest entity	0					0
Other comprehensive income (loss), net of tax	187					187
Balance at end of period at Sep. 30, 2014	16,883	1,565
Balance at end of period at Sep. 30, 2014	$ 15,318		$ 0	$ 14,109	$ 1,181	$ 28