Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020	Dec. 31, 2019
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated other comprehensive income, net of tax, beginning of period	$ 663		$ 663			$ 769
Accumulated other comprehensive income, net of tax, end of period	663		663
Accumulated Net Unrealized Investment Gain (Loss)
Accumulated Other Comprehensive Income Loss Before Tax [Abstract]
Other comprehensive income before reclassification, before tax	(80)	$ 115	(132)	$ 222
Reclassification adjustment, before tax	(8)	(3)	(20)	72
Effect on other comprehensive income, before tax	(88)	112	(152)	294
Accumulated other comprehensive income, before tax, end of period	874	884	874	884
Accumulated Other Comprehensive Income (Loss), Tax [Abstract]
Other comprehensive income before reclassification, tax	(18)	23	(29)	46
Reclassification adjustment, tax	(1)	0	(4)	16
Effect on other comprehensive income, tax	(19)	23	(33)	62
Accumulated other comprehensive income, tax, end of period	182	185	182	185
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated other comprehensive income, net of tax, beginning of period	692	699	692	699
Other comprehensive income before reclassification, net of tax	(62)	92	(103)	176
Reclassification adjustment, net of tax	(7)	(3)	(16)	56
Effect on other comprehensive income, net of tax	(69)	89	(119)	232
Accumulated other comprehensive income, net of tax, end of period	692	699	692	699
Accumulated Defined Benefit Plans Adjustment
Accumulated Other Comprehensive Income Loss Before Tax [Abstract]
Accumulated other comprehensive income, before tax, beginning of period	(36)	(7)	(41)	(9)
Other comprehensive income before reclassification, before tax	0	0	2	0
Reclassification adjustment, before tax	2	0	5	2
Effect on other comprehensive income, before tax	2	0	7	2
Accumulated other comprehensive income, before tax, end of period	(34)	(7)	(34)	(7)
Accumulated Other Comprehensive Income (Loss), Tax [Abstract]
Accumulated other comprehensive income, tax, beginning of period	(6)	0	(7)	0
Other comprehensive income before reclassification, tax	0	0	1	0
Reclassification adjustment, tax	1	0	1	0
Effect on other comprehensive income, tax	1	0	2	0
Accumulated other comprehensive income, tax, end of period	(5)	0	(5)	0
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated other comprehensive income, net of tax, beginning of period	(29)	(7)	(29)	(7)	$ (30)	(34)	$ (7)	$ (9)
Other comprehensive income before reclassification, net of tax	0	0	1	0
Reclassification adjustment, net of tax	1	0	4	2
Effect on other comprehensive income, net of tax	1	0	5	2
Accumulated other comprehensive income, net of tax, end of period	(29)	(7)	(29)	(7)
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	0	(8)	(10)	(13)
Other comprehensive income before reclassification, before tax	0	0	10	5
Reclassification adjustment, before tax	0	0	0	0
Effect on other comprehensive income, before tax	0	0	10	5
Accumulated other comprehensive income, before tax, end of period	0	(8)	0	(8)
Accumulated Other Comprehensive Income (Loss), Tax [Abstract]
Accumulated other comprehensive income, tax, beginning of period	0	(2)	(2)	(3)
Other comprehensive income before reclassification, tax	0	0	2	1
Reclassification adjustment, tax	0	0	0	0
Effect on other comprehensive income, tax	0	0	2	1
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	0	(6)	0	(6)	0	(8)	(6)	(10)
Other comprehensive income before reclassification, net of tax	0	0	8	4
Reclassification adjustment, net of tax	0	0	0	0
Effect on other comprehensive income, net of tax	0	0	8	4
Accumulated other comprehensive income, net of tax, end of period	0	(6)	0	(6)
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	(88)	112	(152)	294
Change in pension obligations, before tax	2	0	7	2
Change in life deferred acquisition costs, life policy reserves and other, before tax	0	0	10	5
Effect on other comprehensive income, before tax	(86)	112	(135)	301
Accumulated other comprehensive income, before tax, end of period	840	869	840	869
Accumulated Other Comprehensive Income (Loss), Tax [Abstract]
Change in unrealized gains, net, on investments available for sale, tax	(19)	23	(33)	62
Change in pension obligations, tax	1	0	2	0
Change in life deferred acquisition costs, life policy reserves and other, tax	0	0	2	1
Effect on other comprehensive income, tax	(18)	23	(29)	63
Accumulated other comprehensive income, tax, end of period	177	183	177	183
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated other comprehensive income, net of tax, beginning of period	663	686	663	686
Change in unrealized gains, net, on investments available for sale, net of tax	(69)	89	(119)	232
Change in pension obligations, net of tax	1	0	5	2
Change in life deferred acquisition costs, life policy reserves and other, net of tax	0	0	8	4
Effect on other comprehensive income, net of tax	(68)	89	(106)	238
Accumulated other comprehensive income, net of tax, end of period	663	686	663	686
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	962	772	1,026	590
Accumulated Other Comprehensive Income (Loss), Tax [Abstract]
Accumulated other comprehensive income, tax, beginning of period	201	162	215	123
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated other comprehensive income, net of tax, beginning of period					761	811	610	467
Previously Reported | Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income Loss Before Tax [Abstract]
Accumulated other comprehensive income, before tax, beginning of period	926	757	975	568
Accumulated Other Comprehensive Income (Loss), Tax [Abstract]
Accumulated other comprehensive income, tax, beginning of period	$ 195	$ 160	$ 206	$ 120
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated other comprehensive income, net of tax, beginning of period					$ 731	$ 769	$ 597	$ 448