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, 2023	Dec. 31, 2022	Dec. 31, 2021
Increase (Decrease) in AOCI, Net of Tax
Beginning balance	$ 3,949,577	$ 2,003,808	$ 8,771,092
Other comprehensive income (loss) before reclassifications, net of tax	(45,186)	1,408,292	569,377
Reclassifications, net of tax	63,080	36,443	(8,620)
Other comprehensive income (loss)	17,894	1,444,735	560,757
Ending balance	4,486,803	3,949,577	2,003,808
Cumulative Effect, Period Of Adoption, Adjusted Balance
Increase (Decrease) in AOCI, Net of Tax
Beginning balance			933,521
Total
Increase (Decrease) in AOCI, Net of Tax
Beginning balance	(2,790,313)	(4,235,048)	3,029,244
Ending balance	(2,772,419)	(2,790,313)	(4,235,048)
Total | Cumulative Effect, Period Of Adoption, Adjusted Balance
Increase (Decrease) in AOCI, Net of Tax
Beginning balance			(4,795,805)
Available for Sale Assets
Increase (Decrease) in AOCI, Net of Tax
Beginning balance	(1,420,672)	2,765,290
Other comprehensive income (loss) before reclassifications, net of tax	529,688	(4,211,540)	(385,231)
Reclassifications, net of tax	63,388	25,578	(25,051)
Other comprehensive income (loss)	593,076	(4,185,962)	(410,282)
Ending balance	(827,596)	(1,420,672)	2,765,290
Available for Sale Assets | Cumulative Effect, Period Of Adoption, Adjusted Balance
Increase (Decrease) in AOCI, Net of Tax
Beginning balance			3,175,572
Future Policy Benefits
Increase (Decrease) in AOCI, Net of Tax
Beginning balance	(1,369,204)	(6,915,910)
Other comprehensive income (loss) before reclassifications, net of tax	(578,187)	5,546,706	913,843
Reclassifications, net of tax	0	0	0
Other comprehensive income (loss)	(578,187)	5,546,706	913,843
Ending balance	(1,947,391)	(1,369,204)	(6,915,910)
Future Policy Benefits | Cumulative Effect, Period Of Adoption, Adjusted Balance
Increase (Decrease) in AOCI, Net of Tax
Beginning balance			(7,829,753)
Foreign Exchange
Increase (Decrease) in AOCI, Net of Tax
Beginning balance	(1,681)	19,248
Other comprehensive income (loss) before reclassifications, net of tax	6,400	(20,929)	(4,054)
Reclassifications, net of tax	0	0	0
Other comprehensive income (loss)	6,400	(20,929)	(4,054)
Ending balance	4,719	(1,681)	19,248
Foreign Exchange | Cumulative Effect, Period Of Adoption, Adjusted Balance
Increase (Decrease) in AOCI, Net of Tax
Beginning balance			23,302
Pension Adjustments
Increase (Decrease) in AOCI, Net of Tax
Beginning balance	1,244	(103,676)
Other comprehensive income (loss) before reclassifications, net of tax	(3,087)	94,055	44,819
Reclassifications, net of tax	(308)	10,865	16,431
Other comprehensive income (loss)	(3,395)	104,920	61,250
Ending balance	$ (2,151)	$ 1,244	(103,676)
Pension Adjustments | Cumulative Effect, Period Of Adoption, Adjusted Balance
Increase (Decrease) in AOCI, Net of Tax
Beginning balance			$ (164,926)