General - Statement of Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net income	$ 931	$ 979	$ 3,074	$ 2,702
Unrealized net capital gains and losses	369	(70)	2,025	(768)
Unrealized foreign currency translation adjustments	(10)	(14)	(1)	(22)
Change in unamortized pension and other postretirement prior service credit	(12)	(15)	(35)	(45)
Other comprehensive income (loss), after-tax	347	(99)	1,989	(835)
Comprehensive income	1,278	880	5,063	1,867
Previously reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net income	1,071	870	3,278	2,521
Unrealized net capital gains and losses	369	(70)	2,025	(768)
Unrealized foreign currency translation adjustments	(12)	(14)	2	(25)
Change in unamortized pension and other postretirement prior service credit	20	68	155	113
Other comprehensive income (loss), after-tax	377	(16)	2,182	(680)
Comprehensive income	1,448	854	5,460	1,841
Impact of change | Impact of change
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net income	(140)	109	(204)	181
Unrealized net capital gains and losses	0	0	0	0
Unrealized foreign currency translation adjustments	2	0	(3)	3
Change in unamortized pension and other postretirement prior service credit	(32)	(83)	(190)	(158)
Other comprehensive income (loss), after-tax	(30)	(83)	(193)	(155)
Comprehensive income	$ (170)	$ 26	$ (397)	$ 26