CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) (Parenthetical) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement of Comprehensive Income [Abstract]
Net unrealized derivative instrument (losses) gains arising during the periods, tax	$ (4)	$ 16	$ (22)	$ 14
Reclassification adjustment for net derivative losses (gains) included in net income, tax	3	(2)	3	(6)
Net unrealized debt securities (losses) gains arising during the periods, tax	(19)	33	(105)	36
Other-than-temporary impairment not recognized in earnings on debt securities, tax	1	6	0	(1)
Reclassification of net debt securities (gains) losses to net income, tax	0	0	(2)	(1)
Amortization of actuarial loss, tax	$ 1	$ 2	$ 2	$ 4