CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) (Parenthetical) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement of Comprehensive Income [Abstract]
Net unrealized derivative instrument (losses) gains arising during the periods, tax	$ (1)	$ 0	$ 13	$ 29
Reclassification adjustment for net derivative gains included in net income, tax	(2)	(4)	(8)	(14)
Net unrealized securities gains (losses) arising during the periods, tax	8	(17)	44	114
Other-than-temporary impairment not recognized in earnings on securities, tax	0	2	(1)	(11)
Reclassification of net securities (gains) losses to net income, tax	0	1	(1)	(1)
Amortization of actuarial loss, tax	$ 2	$ 2	$ 6	$ 5