Business Segments - Schedule of Reconciliation of Segment Operating Information to Consolidated Statement of Operations (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Revenue:
Premium	$ 1,231,007	$ 1,172,593	$ 3,648,304	$ 3,485,002
Net investment income	286,013	284,964	848,796	853,178
Segment revenue	1,517,020	1,457,557	4,497,100	4,338,180
Realized gains (losses)	(4,987)	(2,192)	(23,476)	(26,580)
Other income	955	42	1,073	192
Total revenue	1,512,988	1,455,407	4,474,697	4,311,792
Expenses:
Policy obligations	615,238	682,468	2,119,006	2,137,885
Required interest on reserves	2,372	7,829	7,280	24,358
Amortization of acquisition costs	113,720	103,922	329,914	304,527
Commissions	85,623	77,055	258,399	236,253
Premium taxes	24,209	26,099	74,044	72,475
Non-deferred acquisition costs	48,993	46,535	150,778	138,865
Segment profit or (loss)	626,865	513,649	1,557,679	1,423,817
Insurance administrative expenses:
Salaries	34,265	33,377	102,630	95,406
Other employee costs	10,056	10,455	29,764	28,531
Information technology costs	21,795	20,155	62,286	59,023
Legal costs	4,854	7,609	16,930	19,771
Other administrative costs	18,797	16,869	51,753	48,341
Parent expense	4,105	3,210	10,710	9,166
Stock-based compensation expense	14,603	9,233	40,665	28,590
Interest expense	36,134	31,388	106,011	91,413
Legal proceedings	2,589	3,329	13,365	5,764
Other expenses	498	637	498	2,604
Annuity	(1,965)	(1,721)	(5,818)	(5,384)
Total expenses	1,035,886	1,078,449	3,368,215	3,297,588
Income before income taxes	477,102	376,958	1,106,482	1,014,204
Life
Revenue:
Premium	844,483	818,638	2,513,890	2,438,385
Net investment income	0	0	0	0
Segment revenue	844,483	818,638	2,513,890	2,438,385
Expenses:
Policy obligations	381,511	454,502	1,410,622	1,493,165
Required interest on reserves	(212,454)	(203,875)	(632,150)	(605,397)
Amortization of acquisition costs	98,583	90,070	285,417	263,753
Commissions	42,924	40,092	130,848	118,480
Premium taxes	16,928	16,968	51,621	51,254
Non-deferred acquisition costs	35,383	33,698	108,586	100,613
Segment profit or (loss)	481,608	387,183	1,158,946	1,016,517
Health
Revenue:
Premium	386,524	353,955	1,134,414	1,046,617
Net investment income	0	0	0	0
Segment revenue	386,524	353,955	1,134,414	1,046,617
Expenses:
Policy obligations	227,940	221,926	691,793	629,676
Required interest on reserves	(28,517)	(27,717)	(85,194)	(82,300)
Amortization of acquisition costs	15,137	13,852	44,497	40,774
Commissions	42,699	36,963	127,551	117,773
Premium taxes	7,281	9,131	22,423	21,221
Non-deferred acquisition costs	13,610	12,837	42,192	38,252
Segment profit or (loss)	108,374	86,963	291,152	281,221
Investment
Revenue:
Premium	0	0	0	0
Net investment income	286,013	284,964	848,796	853,178
Segment revenue	286,013	284,964	848,796	853,178
Expenses:
Policy obligations	5,787	6,040	16,591	15,044
Required interest on reserves	243,343	239,421	724,624	712,055
Amortization of acquisition costs	0	0	0	0
Commissions	0	0	0	0
Premium taxes	0	0	0	0
Non-deferred acquisition costs	0	0	0	0
Segment profit or (loss)	$ 36,883	$ 39,503	$ 107,581	$ 126,079