Policyholder Account Balances, Future Policy Benefits and Claims - Balances of and Changes in Liability for Future Policy Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Liability for Future Policy Benefit, Activity [Line Items]
Balance	$ 9,378	$ 8,920		$ 10,386
Liability for Future Policy Benefit, Expected Net Premium [Roll Forward]
Beginning balance	2,027	2,512	$ 2,771
Beginning balance at original discount rate	2,065	2,111	2,217
Effect of changes in cash flow assumptions		(19)	54	(6)
Effect of actual variances from expected experience		(23)	(23)	(40)
Adjusted beginning of year balance		2,023	2,142	2,171
Issuances	244	111	134
Interest accrual	101	106	111
Net premiums collected	(418)	(294)	(305)
Derecognition (lapses)	0	0	0
Ending balance at original discount rate	1,950	2,065	2,111
Effect of changes in discount rate assumptions	3	(38)	401
Ending balance	1,953	2,027	2,512
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Beginning balance	9,519	12,232	13,157
Beginning balance at original discount rate	9,706	9,769	9,920
Effect of changes in cash flow assumptions		(34)	35	(8)
Effect of actual variances from expected experience		(35)	(25)	(120)
Adjusted beginning of year balance		9,637	9,779	9,792
Issuances	244	111	135
Interest accrual	489	496	509
Benefit payments	(729)	(680)	(667)
Derecognition (lapses)	0	0	0
Ending balance at original discount rate	9,641	9,706	9,769
Effect of changes in discount rate assumptions	70	(187)	2,463
Ending balance	9,711	9,519	12,232
Adjustment due to reserve flooring	5	3	1
Reserve for future policy benefits	7,763	7,495	9,721
Less: reinsurance recoverable	4,080	4,060	5,291	4,248
Net liability for future policy benefits, after reinsurance recoverable	3,683	3,435	4,430	6,138
Discounted expected future gross premiums	3,993	4,162	4,786
Expected future gross premiums	5,993	6,422	6,115
Expected future benefit payments	15,810	16,227	16,651
Previously Reported
Liability for Future Policy Benefit, Activity [Line Items]
Balance				8,448
Effect of shadow reserve adjustments
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Effect of changes in cash flow assumptions				(741)
Adjustments for loss contracts (with premiums in excess of gross premiums) under the modified retrospective approach
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Effect of changes in cash flow assumptions				39
Effect of change in deferred profit liability
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Effect of changes in cash flow assumptions				(43)
Effect of remeasurement of the liability at the current single A discount rate
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Effect of changes in cash flow assumptions				2,683
Life Contingent Payout Annuities
Liability for Future Policy Benefit, Activity [Line Items]
Balance				1,537
Liability for Future Policy Benefit, Expected Net Premium [Roll Forward]
Beginning balance	0	0	0
Beginning balance at original discount rate	0	0	0
Effect of changes in cash flow assumptions		0	0	0
Effect of actual variances from expected experience		0	0	0
Adjusted beginning of year balance		0	0	0
Issuances	177	42	38
Interest accrual	1	0	0
Net premiums collected	(178)	(42)	(38)
Derecognition (lapses)	0	0	0
Ending balance at original discount rate	0	0	0
Effect of changes in discount rate assumptions	0	0	0
Ending balance	0	0	0
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Beginning balance	1,065	1,370	1,537
Beginning balance at original discount rate	1,155	1,231	1,321
Effect of changes in cash flow assumptions		0	0	0
Effect of actual variances from expected experience		(10)	(13)	(14)
Adjusted beginning of year balance		1,145	1,218	1,307
Issuances	177	42	39
Interest accrual	50	49	53
Benefit payments	(150)	(154)	(168)
Derecognition (lapses)	0	0	0
Ending balance at original discount rate	1,222	1,155	1,231
Effect of changes in discount rate assumptions	(58)	(90)	139
Ending balance	1,164	1,065	1,370
Adjustment due to reserve flooring	0	0	0
Reserve for future policy benefits	1,164	1,065	1,370
Less: reinsurance recoverable	880	949	1,265	0
Net liability for future policy benefits, after reinsurance recoverable	284	116	105	1,537
Discounted expected future gross premiums	0	0	0
Expected future gross premiums	0	0	0
Expected future benefit payments	$ 1,726	$ 1,595	$ 1,707
Weighted average interest accretion rate	4.20%	4.10%	4.20%
Weighted average discount rate	4.90%	5.20%	2.60%
Weighted average duration of liability (in years)	7 years	6 years	7 years
Life Contingent Payout Annuities | Previously Reported
Liability for Future Policy Benefit, Activity [Line Items]
Balance				1,536
Life Contingent Payout Annuities | Effect of shadow reserve adjustments
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Effect of changes in cash flow assumptions				(175)
Life Contingent Payout Annuities | Adjustments for loss contracts (with premiums in excess of gross premiums) under the modified retrospective approach
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Effect of changes in cash flow assumptions				4
Life Contingent Payout Annuities | Effect of change in deferred profit liability
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Effect of changes in cash flow assumptions				(43)
Life Contingent Payout Annuities | Effect of remeasurement of the liability at the current single A discount rate
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Effect of changes in cash flow assumptions				215
Term and Whole Life Insurance
Liability for Future Policy Benefit, Activity [Line Items]
Balance				898
Liability for Future Policy Benefit, Expected Net Premium [Roll Forward]
Beginning balance	$ 686	$ 777	$ 702
Beginning balance at original discount rate	708	636	536
Effect of changes in cash flow assumptions		(19)	1	0
Effect of actual variances from expected experience		(2)	47	56
Adjusted beginning of year balance		687	684	592
Issuances	55	57	78
Interest accrual	36	34	29
Net premiums collected	(70)	(67)	(63)
Derecognition (lapses)	0	0	0
Ending balance at original discount rate	708	708	636
Effect of changes in discount rate assumptions	(5)	(22)	141
Ending balance	703	686	777
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Beginning balance	1,319	1,598	1,600
Beginning balance at original discount rate	1,313	1,255	1,169
Effect of changes in cash flow assumptions		(18)	(8)	0
Effect of actual variances from expected experience		(1)	52	58
Adjusted beginning of year balance		1,294	1,299	1,227
Issuances	56	57	78
Interest accrual	73	73	70
Benefit payments	(132)	(116)	(120)
Derecognition (lapses)	0	0	0
Ending balance at original discount rate	1,291	1,313	1,255
Effect of changes in discount rate assumptions	34	6	343
Ending balance	1,325	1,319	1,598
Adjustment due to reserve flooring	5	3	1
Reserve for future policy benefits	627	636	822
Less: reinsurance recoverable	440	443	558	601
Net liability for future policy benefits, after reinsurance recoverable	187	193	264	297
Discounted expected future gross premiums	1,764	1,855	2,005
Expected future gross premiums	2,938	3,183	2,815
Expected future benefit payments	$ 2,166	$ 2,234	$ 2,159
Weighted average interest accretion rate	6.20%	6.40%	6.50%
Weighted average discount rate	5.10%	5.50%	2.80%
Weighted average duration of liability (in years)	7 years	7 years	8 years
Term and Whole Life Insurance | Previously Reported
Liability for Future Policy Benefit, Activity [Line Items]
Balance				633
Term and Whole Life Insurance | Effect of shadow reserve adjustments
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Effect of changes in cash flow assumptions				0
Term and Whole Life Insurance | Adjustments for loss contracts (with premiums in excess of gross premiums) under the modified retrospective approach
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Effect of changes in cash flow assumptions				0
Term and Whole Life Insurance | Effect of change in deferred profit liability
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Effect of changes in cash flow assumptions				0
Term and Whole Life Insurance | Effect of remeasurement of the liability at the current single A discount rate
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Effect of changes in cash flow assumptions				265
Disability Income Insurance
Liability for Future Policy Benefit, Activity [Line Items]
Balance				768
Liability for Future Policy Benefit, Expected Net Premium [Roll Forward]
Beginning balance	$ 134	$ 188	$ 238
Beginning balance at original discount rate	137	155	183
Effect of changes in cash flow assumptions		(19)	1	0
Effect of actual variances from expected experience		(18)	(22)	(35)
Adjusted beginning of year balance		100	134	148
Issuances	12	12	18
Interest accrual	5	7	9
Net premiums collected	(12)	(16)	(20)
Derecognition (lapses)	0	0	0
Ending balance at original discount rate	105	137	155
Effect of changes in discount rate assumptions	(1)	(3)	33
Ending balance	104	134	188
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Beginning balance	696	914	1,006
Beginning balance at original discount rate	669	688	714
Effect of changes in cash flow assumptions		(25)	1	0
Effect of actual variances from expected experience		(29)	(28)	(40)
Adjusted beginning of year balance		615	661	674
Issuances	11	12	18
Interest accrual	37	38	39
Benefit payments	(42)	(42)	(43)
Derecognition (lapses)	0	0	0
Ending balance at original discount rate	621	669	688
Effect of changes in discount rate assumptions	40	27	226
Ending balance	661	696	914
Adjustment due to reserve flooring	0	0	0
Reserve for future policy benefits	557	562	726
Less: reinsurance recoverable	22	19	25	24
Net liability for future policy benefits, after reinsurance recoverable	535	543	701	744
Discounted expected future gross premiums	904	926	1,158
Expected future gross premiums	1,269	1,331	1,395
Expected future benefit payments	$ 1,068	$ 1,169	$ 1,217
Weighted average interest accretion rate	6.10%	6.10%	5.90%
Weighted average discount rate	5.10%	5.40%	2.80%
Weighted average duration of liability (in years)	8 years	8 years	9 years
Disability Income Insurance | Previously Reported
Liability for Future Policy Benefit, Activity [Line Items]
Balance				530
Disability Income Insurance | Effect of shadow reserve adjustments
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Effect of changes in cash flow assumptions				0
Disability Income Insurance | Adjustments for loss contracts (with premiums in excess of gross premiums) under the modified retrospective approach
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Effect of changes in cash flow assumptions				0
Disability Income Insurance | Effect of change in deferred profit liability
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Effect of changes in cash flow assumptions				0
Disability Income Insurance | Effect of remeasurement of the liability at the current single A discount rate
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Effect of changes in cash flow assumptions				238
Long Term Care Insurance
Liability for Future Policy Benefit, Activity [Line Items]
Balance				7,183
Liability for Future Policy Benefit, Expected Net Premium [Roll Forward]
Beginning balance	$ 1,207	$ 1,547	$ 1,831
Beginning balance at original discount rate	1,220	1,320	1,498
Effect of changes in cash flow assumptions		19	52	(6)
Effect of actual variances from expected experience		(3)	(48)	(61)
Adjusted beginning of year balance		1,236	1,324	1,431
Issuances	0	0	0
Interest accrual	59	65	73
Net premiums collected	(158)	(169)	(184)
Derecognition (lapses)	0	0	0
Ending balance at original discount rate	1,137	1,220	1,320
Effect of changes in discount rate assumptions	9	(13)	227
Ending balance	1,146	1,207	1,547
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Beginning balance	6,439	8,350	9,014
Beginning balance at original discount rate	6,569	6,595	6,716
Effect of changes in cash flow assumptions		9	42	(8)
Effect of actual variances from expected experience		5	(36)	(124)
Adjusted beginning of year balance		6,583	6,601	6,584
Issuances	0	0	0
Interest accrual	329	336	347
Benefit payments	(405)	(368)	(336)
Derecognition (lapses)	0	0	0
Ending balance at original discount rate	6,507	6,569	6,595
Effect of changes in discount rate assumptions	54	(130)	1,755
Ending balance	6,561	6,439	8,350
Adjustment due to reserve flooring	0	0	0
Reserve for future policy benefits	5,415	5,232	6,803
Less: reinsurance recoverable	2,738	2,649	3,443	3,623
Net liability for future policy benefits, after reinsurance recoverable	2,677	2,583	3,360	3,560
Discounted expected future gross premiums	1,325	1,381	1,623
Expected future gross premiums	1,786	1,908	1,905
Expected future benefit payments	$ 10,850	$ 11,229	$ 11,568
Weighted average interest accretion rate	5.00%	5.20%	5.30%
Weighted average discount rate	5.10%	5.40%	2.90%
Weighted average duration of liability (in years)	8 years	9 years	10 years
Long Term Care Insurance | Previously Reported
Liability for Future Policy Benefit, Activity [Line Items]
Balance				5,749
Long Term Care Insurance | Effect of shadow reserve adjustments
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Effect of changes in cash flow assumptions				(566)
Long Term Care Insurance | Adjustments for loss contracts (with premiums in excess of gross premiums) under the modified retrospective approach
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Effect of changes in cash flow assumptions				35
Long Term Care Insurance | Effect of change in deferred profit liability
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Effect of changes in cash flow assumptions				0
Long Term Care Insurance | Effect of remeasurement of the liability at the current single A discount rate
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Effect of changes in cash flow assumptions				$ 1,965