Business Segments - Schedule of Liabilities by Segment (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Segment Reporting, Other Significant Reconciling Item [Line Items]
Net liability for future policy benefits—long duration health	$ 19,169,687	$ 18,457,263	$ 19,460,353
Unearned and advance premium	270,663	257,631
Policy claims and other benefits payable	540,832	532,832
Debt	2,625,449	2,739,652
Total liabilities	24,839,113	23,770,661
Operating Segments
Segment Reporting, Other Significant Reconciling Item [Line Items]
Net liability for future policy benefits—long duration health	18,589,018	17,800,690
Unearned and advance premium	270,663	257,631
Policy claims and other benefits payable	540,832	532,832
Debt	2,625,449	2,739,652
Other	532,047	468,604
Total segment liabilities	22,558,009	21,799,409
Corporate & Other
Segment Reporting, Other Significant Reconciling Item [Line Items]
Annuity and other corporate	2,281,104	1,971,252
Life
Segment Reporting, Other Significant Reconciling Item [Line Items]
Net liability for future policy benefits—long duration health	15,220,386	14,577,140	15,390,289
Life | Operating Segments
Segment Reporting, Other Significant Reconciling Item [Line Items]
Net liability for future policy benefits—long duration health	16,123,927	15,484,596
Unearned and advance premium	199,011	198,127
Policy claims and other benefits payable	315,595	321,838
Debt	0	0
Other	95,047	96,604
Total segment liabilities	16,733,580	16,101,165
Health
Segment Reporting, Other Significant Reconciling Item [Line Items]
Net liability for future policy benefits—long duration health	2,462,072	2,313,036	$ 2,379,415
Health | Operating Segments
Segment Reporting, Other Significant Reconciling Item [Line Items]
Net liability for future policy benefits—long duration health	2,465,091	2,316,094
Unearned and advance premium	71,652	59,504
Policy claims and other benefits payable	225,237	210,994
Debt	0	0
Other	0	0
Total segment liabilities	2,761,980	2,586,592
Investment | Operating Segments
Segment Reporting, Other Significant Reconciling Item [Line Items]
Net liability for future policy benefits—long duration health	0	0
Unearned and advance premium	0	0
Policy claims and other benefits payable	0	0
Debt	2,625,449	2,739,652
Other	437,000	372,000
Total segment liabilities	$ 3,062,449	$ 3,111,652