Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated other comprehensive income, net of tax, beginning of period	$ 597		$ 597			$ 448
Accumulated other comprehensive income, net of tax, end of period	597		597
Accumulated Net Unrealized Investment Gain (Loss)
Accumulated Other Comprehensive Income Loss Before Tax [Abstract]
Other comprehensive income before reclassification, before tax	506	$ 199	107	$ 443
Reclassification adjustment, before tax	0	1	75	(1)
Effect on other comprehensive income, before tax	506	200	182	442
Accumulated other comprehensive income, before tax, end of period	772	488	772	488
Accumulated Other Comprehensive Income (Loss), Tax [Abstract]
Other comprehensive income before reclassification, tax	107	43	23	93
Reclassification adjustment, tax	0	0	16	0
Effect on other comprehensive income, tax	107	43	39	93
Accumulated other comprehensive income, tax, end of period	162	102	162	102
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated other comprehensive income, net of tax, beginning of period	610	386	610	386
Other comprehensive income before reclassification, net of tax	399	156	84	350
Reclassification adjustment, net of tax	0	1	59	(1)
Effect on other comprehensive income, net of tax	399	157	143	349
Accumulated other comprehensive income, net of tax, end of period	610	386	610	386
Accumulated Defined Benefit Plans Adjustment
Accumulated Other Comprehensive Income Loss Before Tax [Abstract]
Accumulated other comprehensive income, before tax, beginning of period	(8)	(16)	(9)	(16)
Other comprehensive income before reclassification, before tax	0	0	0	0
Reclassification adjustment, before tax	1	1	2	1
Effect on other comprehensive income, before tax	1	1	2	1
Accumulated other comprehensive income, before tax, end of period	(7)	(15)	(7)	(15)
Accumulated Other Comprehensive Income (Loss), Tax [Abstract]
Accumulated other comprehensive income, tax, beginning of period	0	(2)	0	(2)
Other comprehensive income before reclassification, tax	0	0	0	0
Reclassification adjustment, tax	0	0	0	0
Effect on other comprehensive income, tax	0	0	0	0
Accumulated other comprehensive income, tax, end of period	0	(2)	0	(2)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated other comprehensive income, net of tax, beginning of period	(7)	(13)	(7)	(13)	$ (8)	(9)	$ (14)	$ (14)
Other comprehensive income before reclassification, net of tax	0	0	0	0
Reclassification adjustment, net of tax	1	1	2	1
Effect on other comprehensive income, net of tax	1	1	2	1
Accumulated other comprehensive income, net of tax, end of period	(7)	(13)	(7)	(13)
Accumulated Net Unrealized Gain (Loss) on Deferred Costs, Reserves And Other
Accumulated Other Comprehensive Income Loss Before Tax [Abstract]
Accumulated other comprehensive income, before tax, beginning of period	1	(6)	(13)	(1)
Other comprehensive income before reclassification, before tax	(9)	(6)	5	(6)
Reclassification adjustment, before tax	0	1	0	(4)
Effect on other comprehensive income, before tax	(9)	(5)	5	(10)
Accumulated other comprehensive income, before tax, end of period	(8)	(11)	(8)	(11)
Accumulated Other Comprehensive Income (Loss), Tax [Abstract]
Accumulated other comprehensive income, tax, beginning of period	0	(1)	(3)	0
Other comprehensive income before reclassification, tax	(2)	(1)	1	(1)
Reclassification adjustment, tax	0	0	0	(1)
Effect on other comprehensive income, tax	(2)	(1)	1	(2)
Accumulated other comprehensive income, tax, end of period	(2)	(2)	(2)	(2)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated other comprehensive income, net of tax, beginning of period	(6)	(9)	(6)	(9)	1	(10)	(5)	(1)
Other comprehensive income before reclassification, net of tax	(7)	(5)	4	(5)
Reclassification adjustment, net of tax	0	1	0	(3)
Effect on other comprehensive income, net of tax	(7)	(4)	4	(8)
Accumulated other comprehensive income, net of tax, end of period	(6)	(9)	(6)	(9)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income Loss Before Tax [Abstract]
Change in unrealized gains, net, on investments available for sale, before tax	506	200	182	442
Change in pension obligations, before tax	1	1	2	1
Change in life deferred acquisition costs, life policy reserves and other, before tax	(9)	(5)	5	(10)
Effect on other comprehensive income, before tax	498	196	189	433
Accumulated other comprehensive income, before tax, end of period	757	462	757	462
Accumulated Other Comprehensive Income (Loss), Tax [Abstract]
Change in unrealized gains, net, on investments available for sale, tax	107	43	39	93
Change in pension obligations, tax	0	0	0	0
Change in life deferred acquisition costs, life policy reserves and other, tax	(2)	(1)	1	(2)
Effect on other comprehensive income, tax	105	42	40	91
Accumulated other comprehensive income, tax, end of period	160	98	160	98
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated other comprehensive income, net of tax, beginning of period	597	364	597	364
Change in unrealized gains, net, on investments available for sale, net of tax	399	157	143	349
Change in pension obligations, net of tax	1	1	2	1
Change in life deferred acquisition costs, life policy reserves and other, net of tax	(7)	(4)	4	(8)
Effect on other comprehensive income, net of tax	393	154	149	342
Accumulated other comprehensive income, net of tax, end of period	597	364	597	364
Previously Reported | Accumulated Net Unrealized Investment Gain (Loss)
Accumulated Other Comprehensive Income Loss Before Tax [Abstract]
Accumulated other comprehensive income, before tax, beginning of period	266	288	590	46
Accumulated Other Comprehensive Income (Loss), Tax [Abstract]
Accumulated other comprehensive income, tax, beginning of period	55	59	123	9
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated other comprehensive income, net of tax, beginning of period					211	467	229	37
Previously Reported | Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income Loss Before Tax [Abstract]
Accumulated other comprehensive income, before tax, beginning of period	259	266	568	29
Accumulated Other Comprehensive Income (Loss), Tax [Abstract]
Accumulated other comprehensive income, tax, beginning of period	$ 55	$ 56	$ 120	$ 7
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated other comprehensive income, net of tax, beginning of period					$ 204	$ 448	$ 210	$ 22