CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) (Parenthetical) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement of Comprehensive Income [Abstract]
Net unrealized derivative instrument losses arising during the periods, tax	$ (18)	$ (2)
Reclassification adjustment for net derivative losses (gains) included in net income, tax	0	(4)
Net unrealized securities (losses) gains arising during the periods, tax	(86)	3
Other-than-temporary impairment not recognized in earnings on securities, tax	(1)	(7)
Reclassification of net securities gains to net income, tax	(2)	(1)
Amortization of actuarial loss, tax	$ 1	$ 2