CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) (Parenthetical) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Statement of Comprehensive Income [Abstract]
Net unrealized derivative instrument gains arising during the periods, tax	$ 16	$ 8	$ 14	$ 29
Reclassification adjustment for net derivative gains included in net income, tax	(2)	(4)	(6)	(10)
Net unrealized securities available for sale gains arising during the periods, tax	33	39	36	131
Other-than-temporary impairment not recognized in earnings on securities, tax	6	2	(1)	(13)
Reclassification of net securities losses (gains) to net income, tax	0	1	(1)	(2)
Amortization of actuarial loss, tax	$ 2	$ 1	$ 4	$ 3