Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Pre-tax
Other comprehensive income (loss)	$ 855	$ (196)	$ 2,082	$ (933)
Tax
Other comprehensive income (loss)	(180)	41	(440)	197
After-tax
Other comprehensive income (loss)	675	(155)	1,642	(736)
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	921	(249)	2,208	(990)
Less: reclassification adjustment of realized capital gains and losses	57	(80)	108	(106)
Other comprehensive income (loss)	864	(169)	2,100	(884)
Tax
Unrealized net holding gains and losses arising during the period, net of related offsets	(194)	53	(467)	208
Less: reclassification adjustment of realized capital gains and losses	(12)	17	(23)	22
Other comprehensive income (loss)	(182)	36	(444)	186
After-tax
Unrealized net holding gains and losses arising during the period, net of related offsets	727	(196)	1,741	(782)
Less: reclassification adjustment of realized capital gains and losses	45	(63)	85	(84)
Other comprehensive income (loss)	682	(133)	1,656	(698)
Unrealized foreign currency translation adjustments
Pre-tax
Other comprehensive income (loss)	5	(7)	11	(10)
Tax
Other comprehensive income (loss)	(1)	1	(2)	2
After-tax
Other comprehensive income (loss)	4	(6)	9	(8)
Unamortized pension and other postretirement prior service credit (1)
Pre-tax
Other comprehensive income (loss)	(14)	(20)	(29)	(39)
Tax
Other comprehensive income (loss)	3	4	6	9
After-tax
Other comprehensive income (loss)	$ (11)	$ (16)	$ (23)	$ (30)