Consolidated Statements of Comprehensive Income Consolidated Statement of Comprehensive Income (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Other Comprehensive Income (Loss), Available-for-sale Securities, Tax	$ (117)	$ (93)	$ 218
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Tax	(145)	(5)	(106)
Other Comprehensive Income (Loss), Brokered Time Deposits, Tax	0	0	0
Credit Risk Adjustment, Tax	(1)	0	0
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, Tax	$ 52	$ (103)	$ (15)