Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 960	$ 747	$ 3,325	$ 2,612
Other comprehensive (loss) income, net of tax:
Change in net unrealized gains/losses on investments	(36)	9	(353)	190
Change in non-credit component of other-than-temporary impairment losses on investments	(2)	0	(2)	4
Change in net unrealized losses on cash flow hedges	2	(5)	34	(68)
Change in net periodic pension and postretirement costs	7	5	22	13
Foreign currency translation adjustments	0	0	0	3
Other comprehensive (loss) income	(29)	9	(299)	142
Total comprehensive income	$ 931	$ 756	$ 3,026	$ 2,754