Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Pre-tax
Other comprehensive income (loss)	$ 440	$ (127)	$ 2,522	$ (1,060)
Tax
Other comprehensive income (loss)	(93)	28	(533)	225
After-tax
Other comprehensive income (loss)	347	(99)	1,989	(835)
Unrealized net holding gains and losses arising during the period, net of related offsets
Pre-tax
Unrealized net holding gains and losses arising during the period, net of related offsets	603	(116)	2,811	(1,103)
Less: reclassification adjustment of realized capital gains and losses	136	(26)	244	(129)
Other comprehensive income (loss)	467	(90)	2,567	(974)
Tax
Unrealized net holding gains and losses arising during the period, net of related offsets	(127)	25	(593)	233
Less: reclassification adjustment of realized capital gains and losses	(29)	5	(51)	27
Other comprehensive income (loss)	(98)	20	(542)	206
After-tax
Unrealized net holding gains and losses arising during the period, net of related offsets	476	(91)	2,218	(870)
Less: reclassification adjustment of realized capital gains and losses	107	(21)	193	(102)
Other comprehensive income (loss)	369	(70)	2,025	(768)
Unrealized foreign currency translation adjustments
Pre-tax
Other comprehensive income (loss)	(12)	(18)	(1)	(28)
Tax
Other comprehensive income (loss)	2	4	0	6
After-tax
Other comprehensive income (loss)	(10)	(14)	(1)	(22)
Unamortized pension and other postretirement prior service credit
Pre-tax
Other comprehensive income (loss)	(15)	(19)	(44)	(58)
Tax
Other comprehensive income (loss)	3	4	9	13
After-tax
Other comprehensive income (loss)	$ (12)	$ (15)	$ (35)	$ (45)