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, 2024	Dec. 31, 2023	Dec. 31, 2022
Increase (Decrease) in AOCI, Net of Tax
Beginning balance	$ 4,486,803	$ 3,949,577	$ 2,003,808
Other comprehensive income (loss) before reclassifications, net of tax	739,351	(45,186)	1,408,292
Reclassifications, net of tax	3,348	63,080	36,443
Other comprehensive income (loss)	742,699	17,894	1,444,735
Ending balance	5,305,520	4,486,803	3,949,577
Total
Increase (Decrease) in AOCI, Net of Tax
Beginning balance	(2,772,419)	(2,790,313)	(4,235,048)
Ending balance	(2,029,720)	(2,772,419)	(2,790,313)
Available for Sale Assets
Increase (Decrease) in AOCI, Net of Tax
Beginning balance	(827,596)	(1,420,672)	2,765,290
Other comprehensive income (loss) before reclassifications, net of tax	(494,996)	529,688	(4,211,540)
Reclassifications, net of tax	2,974	63,388	25,578
Other comprehensive income (loss)	(492,022)	593,076	(4,185,962)
Ending balance	(1,319,618)	(827,596)	(1,420,672)
Future Policy Benefits
Increase (Decrease) in AOCI, Net of Tax
Beginning balance	(1,947,391)	(1,369,204)	(6,915,910)
Other comprehensive income (loss) before reclassifications, net of tax	1,238,349	(578,187)	5,546,706
Reclassifications, net of tax	0	0	0
Other comprehensive income (loss)	1,238,349	(578,187)	5,546,706
Ending balance	(709,042)	(1,947,391)	(1,369,204)
Foreign Exchange
Increase (Decrease) in AOCI, Net of Tax
Beginning balance	4,719	(1,681)	19,248
Other comprehensive income (loss) before reclassifications, net of tax	(26,476)	6,400	(20,929)
Reclassifications, net of tax	0	0	0
Other comprehensive income (loss)	(26,476)	6,400	(20,929)
Ending balance	(21,757)	4,719	(1,681)
Pension Adjustments
Increase (Decrease) in AOCI, Net of Tax
Beginning balance	(2,151)	1,244	(103,676)
Other comprehensive income (loss) before reclassifications, net of tax	22,474	(3,087)	94,055
Reclassifications, net of tax	374	(308)	10,865
Other comprehensive income (loss)	22,848	(3,395)	104,920
Ending balance	$ 20,697	$ (2,151)	$ 1,244