Supplemental Information about Changes to Accumulated Other Comprehensive Income - Schedule of Change in Balance by Component (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Increase (Decrease) in AOCI, Net of Tax
Beginning balance	$ 5,039,161	$ 3,846,291	$ 4,486,803	$ 3,949,577
Other comprehensive income (loss) before reclassifications, net of tax	271,674	(21,593)	578,671	(218,082)
Reclassifications, net of tax	5,942	38,789	4,128	64,498
Other comprehensive income (loss)	277,616	17,196	582,799	(153,584)
Ending balance	5,227,754	3,980,306	5,227,754	3,980,306
Total
Increase (Decrease) in AOCI, Net of Tax
Beginning balance	(2,467,236)	(2,961,093)	(2,772,419)	(2,790,313)
Ending balance	(2,189,620)	(2,943,897)	(2,189,620)	(2,943,897)
Available for Sale Assets
Increase (Decrease) in AOCI, Net of Tax
Beginning balance	(1,069,185)	(1,016,764)	(827,596)	(1,420,672)
Other comprehensive income (loss) before reclassifications, net of tax	(207,874)	(271,681)	(447,558)	106,481
Reclassifications, net of tax	5,846	39,046	3,941	64,792
Other comprehensive income (loss)	(202,028)	(232,635)	(443,617)	171,273
Ending balance	(1,271,213)	(1,249,399)	(1,271,213)	(1,249,399)
Future Policy Benefits
Increase (Decrease) in AOCI, Net of Tax
Beginning balance	(1,390,759)	(1,938,707)	(1,947,391)	(1,369,204)
Other comprehensive income (loss) before reclassifications, net of tax	479,042	241,906	1,035,674	(327,597)
Reclassifications, net of tax	0	0	0	0
Other comprehensive income (loss)	479,042	241,906	1,035,674	(327,597)
Ending balance	(911,717)	(1,696,801)	(911,717)	(1,696,801)
Foreign Exchange
Increase (Decrease) in AOCI, Net of Tax
Beginning balance	(5,232)	(6,829)	4,719	(1,681)
Other comprehensive income (loss) before reclassifications, net of tax	506	8,182	(9,445)	3,034
Reclassifications, net of tax	0	0	0	0
Other comprehensive income (loss)	506	8,182	(9,445)	3,034
Ending balance	(4,726)	1,353	(4,726)	1,353
Pension Adjustments
Increase (Decrease) in AOCI, Net of Tax
Beginning balance	(2,060)	1,207	(2,151)	1,244
Other comprehensive income (loss) before reclassifications, net of tax	0	0	0	0
Reclassifications, net of tax	96	(257)	187	(294)
Other comprehensive income (loss)	96	(257)	187	(294)
Ending balance	$ (1,964)	$ 950	$ (1,964)	$ 950