Business Segments - Schedule of Reconciliation of Segment Operating Information to Consolidated Statement of Operations (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Revenue:
Premium	$ 1,199,654	$ 1,145,284
Net investment income	280,614	282,578
Segment revenue	1,480,268	1,427,862
Realized gains (losses)	85	(11,799)
Other income	69	76
Total revenue	1,480,422	1,416,139
Expenses:
Policy obligations	749,079	725,666
Required interest on reserves	2,528	8,445
Amortization of acquisition costs	105,152	99,079
Commissions	88,454	77,839
Premium taxes	25,504	23,902
Non-deferred acquisition costs	51,696	46,365
Segment profit or (loss)	457,855	446,566
Insurance administrative expenses:
Salaries	33,688	31,174
Other employee costs	10,301	10,013
Information technology costs	20,936	18,307
Legal costs	6,249	5,273
Other administrative costs	16,375	15,644
Parent expense	3,050	2,826
Stock-based compensation expense	12,019	9,267
Interest expense	34,992	28,621
Legal proceedings	6,128	0
Non-operating expenses	0	710
Annuity	(1,810)	(1,915)
Total expenses	1,164,341	1,101,216
Income before income taxes	316,081	314,923
Life
Revenue:
Premium	829,863	804,265
Net investment income	0	0
Segment revenue	829,863	804,265
Expenses:
Policy obligations	509,756	519,871
Required interest on reserves	(208,536)	(199,707)
Amortization of acquisition costs	90,633	85,768
Commissions	45,567	38,690
Premium taxes	18,011	17,086
Non-deferred acquisition costs	37,168	33,546
Segment profit or (loss)	337,264	309,011
Health
Revenue:
Premium	369,791	341,019
Net investment income	0	0
Segment revenue	369,791	341,019
Expenses:
Policy obligations	233,929	202,327
Required interest on reserves	(28,286)	(27,173)
Amortization of acquisition costs	14,519	13,311
Commissions	42,887	39,149
Premium taxes	7,493	6,816
Non-deferred acquisition costs	14,528	12,819
Segment profit or (loss)	84,721	93,770
Investment
Revenue:
Premium	0	0
Net investment income	280,614	282,578
Segment revenue	280,614	282,578
Expenses:
Policy obligations	5,394	3,468
Required interest on reserves	239,350	235,325
Amortization of acquisition costs	0	0
Commissions	0	0
Premium taxes	0	0
Non-deferred acquisition costs	0	0
Segment profit or (loss)	$ 35,870	$ 43,785