Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Statement of Comprehensive Income [Abstract]
Income before income taxes and equity in undistributed income of subsidiaries	$ 964,177	$ 989,360	$ 484,665
Net income, income tax	(206,275)	(228,893)	(110,970)
Net income	757,902	760,467	373,695
Before-tax Amount
Net unrealized gains (losses) arising during the period	(1,522,047)	(234,550)	108,626
Reclassification adjustment for realized (gains) losses included in net income	0	799	(78,931)
Net change	(1,522,047)	(233,751)	29,695
Income Tax
Net unrealized gains (losses) arising during the period	369,764	60,304	(28,135)
Reclassification adjustment for realized (gains) losses included in net income	0	(202)	20,443
Net change	369,764	60,102	(7,692)
Net of Tax Amount
Net unrealized gains (losses) arising during the period	(1,152,283)	(174,246)	80,491
Reclassification adjustment for realized (gains) losses included in net income	0	597	(58,488)
Net change	(1,152,283)	(173,649)	22,003
Before-tax Amount
Net unrealized gains (losses) arising during the period	(298,289)	(77,948)	99,193
Reclassification adjustment for realized (gains) losses included in net income	24,057	(12,862)	(2,765)
Net change	(274,232)	(90,810)	96,428
Income Tax
Net unrealized gains (losses) arising during the period	72,574	20,243	(25,691)
Reclassification adjustment for realized (gains) losses included in net income	(5,855)	3,260	716
Net change	66,719	23,503	(24,975)
Net of Tax Amount
Net unrealized gains (losses) arising during the period	(225,715)	(57,705)	73,502
Reclassification adjustment for realized (gains) losses included in net income	18,202	(9,602)	(2,049)
Net change	(207,513)	(67,307)	71,453
Before-tax Amount
Actuarial losses arising during the period	0	0	0
Reclassification adjustment for realized gains included in net income	0	0	(618)
Net change	0	0	(618)
Income Tax
Actuarial losses arising during the period	0	0	0
Reclassification adjustment for realized gains included in net income	0	0	156
Net change	0	0	156
Net of Tax Amount
Actuarial losses arising during the period	0	0	0
Reclassification adjustment for realized gains included in net income	0	0	(462)
Net change	0	0	(462)
Total other comprehensive income (loss)	(1,796,279)	(324,561)	125,505
Other comprehensive income (loss), income tax	436,483	83,605	(32,511)
Other comprehensive income (loss)	(1,359,796)	(240,956)	92,994
Comprehensive income (loss)	$ (601,894)	$ 519,511	$ 466,689