Liability For Future Policy Benefits (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Other adjustments	$ 12,005	$ 4,402
Balance, end of period	18,227,141	18,505,583
Interest accrual	128,241	117,307
Other Businesses
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Balance, end of period	1,675	2,055
Nonparticipating Traditional And Limited-Pay Business
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Gain in net income		23,000
Loss in net income		(24,000)
Term Life
Liability for Future Policy Benefit, Expected Net Premium [Roll Forward]
Balance, beginning of period	10,927,833	10,911,794
Effect of cumulative changes in discount rate assumptions, beginning of period	225,711	554,896
Balance at original discount rate, beginning of period	11,153,544	11,466,690
Effect of actual variances from expected experience and other activity			$ (54,196)	$ (4,111)
Adjusted balance, beginning of period	11,099,348	11,462,579
Issuances	192,492	132,627
Net premiums / considerations collected	(329,743)	(338,534)
Interest accrual	129,053	131,333
Other adjustments	(78)
Balance at original discount rate, end of period	11,091,072	11,388,005
Effect of cumulative changes in discount rate assumptions, end of period	(434,791)	(312,681)
Balance, end of period	10,656,281	11,075,324
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Balance, beginning of period	18,426,207	17,835,251
Effect of cumulative changes in discount rate assumptions, beginning of period	331,571	962,034
Balance at original discount rate, beginning of period	18,757,778	18,797,285
Effect of actual variances from expected experience and other activity			(65,431)	(13,802)
Adjusted balance, beginning of period	18,692,347	18,783,483
Issuances	192,492	132,627
Interest accrual	223,989	223,841
Benefit payments	(368,247)	(378,918)
Other adjustments	(23)	1,278
Balance at original discount rate, end of period	18,740,558	18,762,311
Effect of cumulative changes in discount rate assumptions, end of period	(742,789)	(474,265)
Balance, end of period	17,997,769	18,288,046
Balance, end of period, pre-flooring	7,341,488	7,212,722
Flooring impact, end of period	44	0
Balance, end of period, post flooring	7,341,532	7,212,722
Reinsurance recoverable	6,650,332	6,719,094
Balance after reinsurance recoverables, end of period, post-flooring	691,200	493,628
Term Life | Gross Basis
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Undiscounted expected future gross premiums	21,812,112	22,077,087
Discounted expected future gross premiums (at original discount rate)	14,968,218	15,222,212
Discounted expected future gross premiums (at current discount rate)	14,408,614	14,816,791
Undiscounted expected future benefits and expenses	29,069,972	29,198,512
Interest accrual	94,935	92,508
Gross Premiums	$ 446,853	$ 449,968
Weighted-average duration of the liability in years (at original discount rate)	10 years	10 years
Weighted-average duration of the liability in years (at current discount rate)	10 years	10 years
Weighted-average interest rate (at original discount rate)	5.16%	5.21%
Weighted-average interest rate (at current discount rate)	5.29%	5.05%
Fixed Annuities
Liability for Future Policy Benefit, Expected Net Premium [Roll Forward]
Balance, beginning of period	$ 0	$ 0
Effect of cumulative changes in discount rate assumptions, beginning of period	0	0
Balance at original discount rate, beginning of period	0	0
Effect of actual variances from expected experience and other activity			(290)	(599)
Issuances	8,595	9,560
Net premiums / considerations collected	(8,305)	(8,961)
Interest accrual	0	0
Other adjustments	0
Balance at original discount rate, end of period	0	0
Effect of cumulative changes in discount rate assumptions, end of period	0	0
Balance, end of period	0	0
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Balance, beginning of period	228,788	204,727
Effect of cumulative changes in discount rate assumptions, beginning of period	19,521	24,876
Balance at original discount rate, beginning of period	248,309	229,603
Effect of actual variances from expected experience and other activity			(369)	1,427
Adjusted balance, beginning of period	247,940	231,030
Issuances	8,595	9,560
Interest accrual	2,204	2,137
Benefit payments	(7,544)	(7,418)
Other adjustments	(34)	(41)
Balance at original discount rate, end of period	251,161	235,268
Effect of cumulative changes in discount rate assumptions, end of period	(23,464)	(19,786)
Balance, end of period	227,697	215,482
Balance, end of period, pre-flooring	227,697	215,482
Flooring impact, end of period	0	0
Balance, end of period, post flooring	227,697	215,482
Reinsurance recoverable	18,428	17,336
Balance after reinsurance recoverables, end of period, post-flooring	209,269	198,146
Fixed Annuities | Gross Basis
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Undiscounted expected future gross premiums	0	0
Discounted expected future gross premiums (at original discount rate)	0	0
Discounted expected future gross premiums (at current discount rate)	0	0
Undiscounted expected future benefits and expenses	336,830	316,153
Interest accrual	2,204	2,137
Gross Premiums	$ 8,572	$ 10,891
Weighted-average duration of the liability in years (at original discount rate)	7 years	7 years
Weighted-average duration of the liability in years (at current discount rate)	6 years	6 years
Weighted-average interest rate (at original discount rate)	3.76%	3.69%
Weighted-average interest rate (at current discount rate)	5.26%	5.01%
Fixed Annuity Netting
Liability for Future Policy Benefit, Expected Net Premium [Roll Forward]
Adjusted balance, beginning of period	$ (290)	$ (599)
Term Life And Fixed Annuities
Liability for Future Policy Benefit, Expected Net Premium [Roll Forward]
Balance, beginning of period	10,927,833	10,911,794
Effect of cumulative changes in discount rate assumptions, beginning of period	225,711	554,896
Balance at original discount rate, beginning of period	11,153,544	11,466,690
Effect of actual variances from expected experience and other activity			(54,486)	(4,710)
Adjusted balance, beginning of period	11,099,058	11,461,980
Issuances	201,087	142,187
Net premiums / considerations collected	(338,048)	(347,495)
Interest accrual	129,053	131,333
Other adjustments	(78)
Balance at original discount rate, end of period	11,091,072	11,388,005
Effect of cumulative changes in discount rate assumptions, end of period	(434,791)	(312,681)
Balance, end of period	10,656,281	11,075,324
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Balance, end of period, pre-flooring	7,569,185	7,428,204
Flooring impact, end of period	44	0
Balance, end of period, post flooring	7,569,229	7,428,204
Reinsurance recoverable	6,668,760	6,736,430
Balance after reinsurance recoverables, end of period, post-flooring	900,469	691,774
Term Life And Fixed Annuities | Total
Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward]
Balance, beginning of period	18,654,995	18,039,978
Effect of cumulative changes in discount rate assumptions, beginning of period	351,092	986,910
Balance at original discount rate, beginning of period	19,006,087	19,026,888
Effect of actual variances from expected experience and other activity			$ (65,800)	$ (12,375)
Adjusted balance, beginning of period	18,940,287	19,014,513
Issuances	201,087	142,187
Interest accrual	226,193	225,978
Benefit payments	(375,791)	(386,336)
Other adjustments	(57)	1,237
Balance at original discount rate, end of period	18,991,719	18,997,579
Effect of cumulative changes in discount rate assumptions, end of period	(766,253)	(494,051)
Balance, end of period	$ 18,225,466	$ 18,503,528