Liability for Future Policyholder Benefits - Reconciliation of the Net Liability for Future Benefits to Life and Health Insurance Reserves (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024	Dec. 31, 2023
Insurance [Abstract]
Net Liability for Future Policyholder Benefits, post-flooring	$ 2,665,300	$ 2,798,100
Deferred Profit Liability	428,800	357,500	$ 412,100	$ 337,800
A&H and Other Reserves	135,400	138,700
Total Life and Health Insurance Reserves	3,229,500	3,294,300
Term Life Insurance
Liability for Future Policy Benefit, by Product Segment [Line Items]
Net Liability for Future Policyholder Benefits, post-flooring	10,137,400	10,225,900
Expected Future Gross Premiums, undiscounted	4,002,100	4,136,000
Expected Future Gross Premiums, discounted	2,671,600	2,758,300
Gross Premiums or Assessments	101,700	101,300
Interest Expense	$ 34,700	$ 35,000
Interest Accretion Rate	4.53%	4.55%
Current Discount Rate	5.72%	5.40%