Supplemental Information about Changes to Accumulated Other Comprehensive Income - Schedule of Change in Balance by Component (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 5,305,520	$ 4,486,803	$ 3,949,577
Other comprehensive income (loss) before reclassifications, net of tax	246,451	739,351	(45,186)
Reclassifications, net of tax	11,825	3,348	63,080
Other comprehensive income (loss)	258,276	742,699	17,894
Ending balance	5,974,579	5,305,520	4,486,803
Total
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(2,029,720)	(2,772,419)	(2,790,313)
Ending balance	(1,771,444)	(2,029,720)	(2,772,419)
Available for Sale Assets
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(1,319,618)	(827,596)	(1,420,672)
Other comprehensive income (loss) before reclassifications, net of tax	338,012	(494,996)	529,688
Reclassifications, net of tax	11,624	2,974	63,388
Other comprehensive income (loss)	349,636	(492,022)	593,076
Ending balance	(969,982)	(1,319,618)	(827,596)
Future Policy Benefits
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(709,042)	(1,947,391)	(1,369,204)
Other comprehensive income (loss) before reclassifications, net of tax	(112,586)	1,238,349	(578,187)
Reclassifications, net of tax	0	0	0
Other comprehensive income (loss)	(112,586)	1,238,349	(578,187)
Ending balance	(821,628)	(709,042)	(1,947,391)
Foreign Exchange
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(21,757)	4,719	(1,681)
Other comprehensive income (loss) before reclassifications, net of tax	12,713	(26,476)	6,400
Reclassifications, net of tax	0	0	0
Other comprehensive income (loss)	12,713	(26,476)	6,400
Ending balance	(9,044)	(21,757)	4,719
Pension Adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	20,697	(2,151)	1,244
Other comprehensive income (loss) before reclassifications, net of tax	8,312	22,474	(3,087)
Reclassifications, net of tax	201	374	(308)
Other comprehensive income (loss)	8,513	22,848	(3,395)
Ending balance	$ 29,210	$ 20,697	$ (2,151)