Business Segments - Schedule of Liabilities by Segment (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Segment Reporting, Other Significant Reconciling Item [Line Items]
Net liability for future policy benefits—long duration health	$ 18,457,263	$ 19,460,353	$ 18,097,341
Unearned and advance premium	257,631	254,567
Policy claims and other benefits payable	532,832	514,875
Debt	2,739,652	2,115,672
Total liabilities	23,770,661	23,564,696
Operating Segments
Segment Reporting, Other Significant Reconciling Item [Line Items]
Net liability for future policy benefits—long duration health	17,800,690	18,687,314
Unearned and advance premium	257,631	254,567
Policy claims and other benefits payable	532,832	514,875
Debt	2,739,652	2,115,672
Other	468,604	236,958
Total segment liabilities	21,799,409	21,809,386
Corporate & Other
Segment Reporting, Other Significant Reconciling Item [Line Items]
Annuity and other corporate	1,971,252	1,755,310
Life
Segment Reporting, Other Significant Reconciling Item [Line Items]
Net liability for future policy benefits—long duration health	14,577,140	15,390,289	14,014,147
Life | Operating Segments
Segment Reporting, Other Significant Reconciling Item [Line Items]
Net liability for future policy benefits—long duration health	15,484,596	16,304,797
Unearned and advance premium	198,127	196,630
Policy claims and other benefits payable	321,838	320,066
Debt	0	0
Other	96,604	98,958
Total segment liabilities	16,101,165	16,920,451
Health
Segment Reporting, Other Significant Reconciling Item [Line Items]
Net liability for future policy benefits—long duration health	2,313,036	2,379,415	$ 2,203,789
Health | Operating Segments
Segment Reporting, Other Significant Reconciling Item [Line Items]
Net liability for future policy benefits—long duration health	2,316,094	2,382,517
Unearned and advance premium	59,504	57,937
Policy claims and other benefits payable	210,994	194,809
Debt	0	0
Other	0	0
Total segment liabilities	2,586,592	2,635,263
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	2,739,652	2,115,672
Other	372,000	138,000
Total segment liabilities	$ 3,111,652	$ 2,253,672