CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Net income	$ 791	$ 1,005	$ 942	$ 1,013	$ 920	$ 1,114	$ 863	$ 1,153	$ 3,751	$ 4,050	$ 4,428
After Tax
Net unrealized gains (losses) on securities available for sale									(166)	(248)	304
Net changes in securities held to maturity									104	96	76
Net unrealized gains (losses) on cash flow hedges									(198)	110	120
Foreign currency translation adjustments									(79)	(135)	(48)
Other									6	(9)	(10)
Other comprehensive income (loss), net of tax									(333)	(186)	442
Comprehensive income									$ 3,418	$ 3,864	$ 4,870