Parent Company Financial Statements (Parent Company Condensed Income Statements) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Other income	$ 302	$ 362	$ 299
Interest expense	768	891	1,060
Other expenses	5,921	5,837	5,828
Income tax benefit	(760)	(1,395)	(764)
Net Income	2,226	1,729	2,028
Noncontrolling interests	75	50	49
Dividends on preferred stock	148	117	63
Net income available to common shareholders	2,003	1,562	1,916
Parent Company [Member]
Dividends from banking subsidiaries	1,636	1,220	1,720
Dividends from other subsidiaries	71	79	81
Interest and other income from subsidiaries	67	67	79
Other income	7	14	1
Total income	1,781	1,380	1,881
Interest expense	148	219	239
Other expenses	55	50	52
Total expense	203	269	291
Income before income taxes and equity in undistributed earnings of subsidiaries	1,578	1,111	1,590
Income tax benefit	43	2	20
Income before equity in undistributed earnings of subsidiaries	1,621	1,113	1,610
Equity in earnings of subsidiaries in excess of dividends from subsidiaries	605	616	418
Net Income	2,226	1,729	2,028
Noncontrolling interests	75	50	49
Dividends on preferred stock	148	117	63
Net income available to common shareholders	$ 2,003	$ 1,562	$ 1,916