Business Segments - Schedule of Assets by Segment (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Jun. 30, 2025	Dec. 31, 2024	Sep. 30, 2024	Jun. 30, 2024	Dec. 31, 2023
Segment Reporting, Asset Reconciling Item [Line Items]
Accrued investment income	$ 284,888		$ 269,791
Deferred acquisition costs	6,872,342		6,495,589	$ 6,386,682
Goodwill	490,446		490,446
Total assets	30,527,616		29,076,181
Life
Segment Reporting, Asset Reconciling Item [Line Items]
Deferred acquisition costs	6,035,556	$ 5,931,048	5,700,755	5,607,729	$ 5,495,593	$ 5,271,775
Health
Segment Reporting, Asset Reconciling Item [Line Items]
Deferred acquisition costs	836,449	$ 823,082	793,421	$ 777,162	$ 762,523	$ 734,735
Operating Segments
Segment Reporting, Asset Reconciling Item [Line Items]
Cash and invested assets	20,629,430		19,736,888
Accrued investment income	284,888		269,791
Deferred acquisition costs	6,872,005		6,494,176
Goodwill	490,446		490,446
Total segment assets	28,276,769		26,991,301
Operating Segments | Life
Segment Reporting, Asset Reconciling Item [Line Items]
Cash and invested assets	0		0
Accrued investment income	0		0
Deferred acquisition costs	6,035,556		5,700,755
Goodwill	309,609		309,609
Total segment assets	6,345,165		6,010,364
Operating Segments | Health
Segment Reporting, Asset Reconciling Item [Line Items]
Cash and invested assets	0		0
Accrued investment income	0		0
Deferred acquisition costs	836,449		793,421
Goodwill	180,837		180,837
Total segment assets	1,017,286		974,258
Operating Segments | Investment
Segment Reporting, Asset Reconciling Item [Line Items]
Cash and invested assets	20,629,430		19,736,888
Accrued investment income	284,888		269,791
Deferred acquisition costs	0		0
Goodwill	0		0
Total segment assets	20,914,318		20,006,679
Corporate & Other
Segment Reporting, Asset Reconciling Item [Line Items]
Annuity and other corporate	$ 2,250,847		$ 2,084,880