Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated other comprehensive income, net of tax, beginning of period	$ 686		$ 686			$ 448
Accumulated other comprehensive income, net of tax, end of period	686		686
Accumulated Net Unrealized Investment Gain (Loss)
Accumulated Other Comprehensive Income Loss Before Tax [Abstract]
Other comprehensive income before reclassification, before tax	115	$ 99	222	$ 542
Reclassification adjustment, before tax	(3)	1	72	0
Effect on other comprehensive income, before tax	112	100	294	542
Accumulated other comprehensive income, before tax, end of period	884	588	884	588
Accumulated Other Comprehensive Income (Loss), Tax [Abstract]
Other comprehensive income before reclassification, tax	23	21	46	114
Reclassification adjustment, tax	0	0	16	0
Effect on other comprehensive income, tax	23	21	62	114
Accumulated other comprehensive income, tax, end of period	185	123	185	123
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated other comprehensive income, net of tax, beginning of period	699	465	699	465
Other comprehensive income before reclassification, net of tax	92	78	176	428
Reclassification adjustment, net of tax	(3)	1	56	0
Effect on other comprehensive income, net of tax	89	79	232	428
Accumulated other comprehensive income, net of tax, end of period	699	465	699	465
Accumulated Defined Benefit Plans Adjustment
Accumulated Other Comprehensive Income Loss Before Tax [Abstract]
Accumulated other comprehensive income, before tax, beginning of period	(7)	(15)	(9)	(16)
Other comprehensive income before reclassification, before tax	0	0	0	0
Reclassification adjustment, before tax	0	0	2	1
Effect on other comprehensive income, before tax	0	0	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)	$ (7)	(9)	$ (13)	$ (14)
Other comprehensive income before reclassification, net of tax	0	0	0	0
Reclassification adjustment, net of tax	0	0	2	1
Effect on other comprehensive income, net of tax	0	0	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	(8)	(11)	(13)	(1)
Other comprehensive income before reclassification, before tax	0	(3)	5	(9)
Reclassification adjustment, before tax	0	2	0	(2)
Effect on other comprehensive income, before tax	0	(1)	5	(11)
Accumulated other comprehensive income, before tax, end of period	(8)	(12)	(8)	(12)
Accumulated Other Comprehensive Income (Loss), Tax [Abstract]
Accumulated other comprehensive income, tax, beginning of period	(2)	(2)	(3)	0
Other comprehensive income before reclassification, tax	0	0	1	(2)
Reclassification adjustment, tax	0	0	0	0
Effect on other comprehensive income, tax	0	0	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)	(10)	(6)	(10)	(6)	(10)	(9)	(1)
Other comprehensive income before reclassification, net of tax	0	(3)	4	(7)
Reclassification adjustment, net of tax	0	2	0	(2)
Effect on other comprehensive income, net of tax	0	(1)	4	(9)
Accumulated other comprehensive income, net of tax, end of period	(6)	(10)	(6)	(10)
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	112	100	294	542
Change in pension obligations, before tax	0	0	2	1
Change in life deferred acquisition costs, life policy reserves and other, before tax	0	(1)	5	(11)
Effect on other comprehensive income, before tax	112	99	301	532
Accumulated other comprehensive income, before tax, end of period	869	561	869	561
Accumulated Other Comprehensive Income (Loss), Tax [Abstract]
Change in unrealized gains, net, on investments available for sale, tax	23	21	62	114
Change in pension obligations, tax	0	0	0	0
Change in life deferred acquisition costs, life policy reserves and other, tax	0	0	1	(2)
Effect on other comprehensive income, tax	23	21	63	112
Accumulated other comprehensive income, tax, end of period	183	119	183	119
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated other comprehensive income, net of tax, beginning of period	686	442	686	442
Change in unrealized gains, net, on investments available for sale, net of tax	89	79	232	428
Change in pension obligations, net of tax	0	0	2	1
Change in life deferred acquisition costs, life policy reserves and other, net of tax	0	(1)	4	(9)
Effect on other comprehensive income, net of tax	89	78	238	420
Accumulated other comprehensive income, net of tax, end of period	686	442	686	442
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	772	488	590	46
Accumulated Other Comprehensive Income (Loss), Tax [Abstract]
Accumulated other comprehensive income, tax, beginning of period	162	102	123	9
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated other comprehensive income, net of tax, beginning of period					610	467	386	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	757	462	568	29
Accumulated Other Comprehensive Income (Loss), Tax [Abstract]
Accumulated other comprehensive income, tax, beginning of period	$ 160	$ 98	$ 120	$ 7
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated other comprehensive income, net of tax, beginning of period					$ 597	$ 448	$ 364	$ 22