Parent Company Financial Statements - Statement of Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Condensed Financial Statements, Captions [Line Items]
Total revenue	$ 10,207	$ 10,360	$ 10,274
Other expenses	584	1,018	751
Total expenses	8,077	8,050	7,827
Income tax expense (benefit)	(22)	318	415
Net income	2,143	1,980	2,022
Parent Company
Condensed Financial Statements, Captions [Line Items]
Cash dividends from consolidated banking subsidiary	640	585	1,470
Cash dividends from consolidated non-banking subsidiaries and unconsolidated entities	75	171	138
Other, net	92	73	63
Total revenue	807	829	1,671
Interest expense	249	209	193
Other expenses	107	310	55
Total expenses	356	519	248
Income tax expense (benefit)	(47)	(186)	(83)
Income (loss) before equity in undistributed income of consolidated subsidiaries and unconsolidated entities	498	496	1,506
Consolidated banking subsidiary	1,629	1,384	360
Consolidated non-banking subsidiaries and unconsolidated entities	16	100	156
Net income	$ 2,143	$ 1,980	$ 2,022