CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statement of Comprehensive Income [Abstract]
Net income	$ 920	$ 1,114	$ 863	$ 1,153	$ 999	$ 1,081	$ 1,194	$ 1,154	$ 4,050	$ 4,428	$ 4,121
After Tax
Net unrealized gains (losses) on securities available for sale									(248)	304	(597)
Net changes in securities held to maturity									96	76	(897)
Net unrealized gains (losses) on cash flow hedges									110	120	(155)
Foreign currency translation adjustments									(135)	(48)	8
Other									(9)	(10)	30
Other comprehensive income (loss), net of tax									(186)	442	(1,611)
Comprehensive income									$ 3,864	$ 4,870	$ 2,510