Business Segments - Schedule of Reconciliation of Segment Operating Information to Consolidated Statement of Operations (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Revenue:
Premium	$ 1,270,113	$ 1,199,654
Net investment income	289,824	280,614
Segment revenue	1,559,937	1,480,268
Realized gains (losses)	(1,478)	85
Other income	1,160	69
Total revenue	1,559,619	1,480,422
Expenses:
Policy obligations	788,130	749,079
Required interest on reserves	2,204	2,528
Amortization of acquisition costs	118,282	105,152
Commissions	90,992	88,454
Premium taxes	25,996	25,504
Non-deferred acquisition costs	54,117	51,696
Segment profit or (loss)	480,216	457,855
Insurance administrative expenses:
Salaries	35,379	33,688
Other employee costs	13,771	10,301
Information technology costs	21,872	20,936
Legal costs	3,192	6,249
Other administrative costs	20,072	16,375
Parent expense	3,533	3,050
Stock-based compensation expense	13,603	12,019
Interest expense	34,000	34,992
Legal proceedings	2,222	6,128
Other expenses	91	0
Annuity	(1,969)	(1,810)
Total expenses	1,225,487	1,164,341
Income before income taxes	334,132	316,081
Life
Revenue:
Premium	853,205	829,863
Net investment income	0	0
Segment revenue	853,205	829,863
Expenses:
Policy obligations	518,850	509,756
Required interest on reserves	(216,538)	(208,536)
Amortization of acquisition costs	102,694	90,633
Commissions	43,547	45,567
Premium taxes	17,773	18,011
Non-deferred acquisition costs	37,821	37,168
Segment profit or (loss)	349,058	337,264
Health
Revenue:
Premium	416,908	369,791
Net investment income	0	0
Segment revenue	416,908	369,791
Expenses:
Policy obligations	263,734	233,929
Required interest on reserves	(28,882)	(28,286)
Amortization of acquisition costs	15,588	14,519
Commissions	47,445	42,887
Premium taxes	8,223	7,493
Non-deferred acquisition costs	16,296	14,528
Segment profit or (loss)	94,504	84,721
Investment
Revenue:
Premium	0	0
Net investment income	289,824	280,614
Segment revenue	289,824	280,614
Expenses:
Policy obligations	5,546	5,394
Required interest on reserves	247,624	239,350
Amortization of acquisition costs	0	0
Commissions	0	0
Premium taxes	0	0
Non-deferred acquisition costs	0	0
Segment profit or (loss)	$ 36,654	$ 35,870