Supplemental Information about Changes to Accumulated Other Comprehensive Income - Schedule of Change in Balance by Component (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Increase (Decrease) in AOCI, Net of Tax
Beginning balance	$ 3,949,577	$ 2,003,808
Other comprehensive income (loss) before reclassifications, net of tax	(196,489)	408,511
Reclassifications, net of tax	25,709	(469)
Other comprehensive income (loss)	(170,780)	408,042
Ending balance	3,846,291	2,544,275
Total
Increase (Decrease) in AOCI, Net of Tax
Beginning balance	(2,790,313)	(4,235,048)
Ending balance	(2,961,093)	(3,827,006)
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	378,162	(1,811,185)
Reclassifications, net of tax	25,746	(3,184)
Other comprehensive income (loss)	403,908	(1,814,369)
Ending balance	(1,016,764)	950,921
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	(569,503)	2,216,355
Reclassifications, net of tax	0	0
Other comprehensive income (loss)	(569,503)	2,216,355
Ending balance	(1,938,707)	(4,699,555)
Foreign Exchange
Increase (Decrease) in AOCI, Net of Tax
Beginning balance	(1,681)	19,248
Other comprehensive income (loss) before reclassifications, net of tax	(5,148)	3,341
Reclassifications, net of tax	0	0
Other comprehensive income (loss)	(5,148)	3,341
Ending balance	(6,829)	22,589
Pension Adjustments
Increase (Decrease) in AOCI, Net of Tax
Beginning balance	1,244	(103,676)
Other comprehensive income (loss) before reclassifications, net of tax	0	0
Reclassifications, net of tax	(37)	2,715
Other comprehensive income (loss)	(37)	2,715
Ending balance	$ 1,207	$ (100,961)