Condensed Consolidated Statements Of Comprehensive Income - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 491	$ 1,115
Other comprehensive (loss) income:
Change in gross unrealized investment gains/losses	(203)	38
Effect of income taxes	52	(14)
Total change in unrealized investment gains/losses, net of tax	(151)	24
Reclassification adjustment for net realized gains included in investment income	(29)	(26)
Effect of income taxes	7	10
Total reclassification adjustment, net of tax	(22)	(16)
Other comprehensive (loss) income, net of tax	(173)	8
Comprehensive income	$ 318	$ 1,123