Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	Common stock:	Additional paid-in capital:	Accumulated other comprehensive income:	Unrealized gains (losses) on non-impaired securities:	Unrealized losses on impaired held-to-maturity securities:	Unrealized losses on impaired available-for-sale securities:	Unrealized losses on impaired available-for-sale securities: Cumulative Effect, Period of Adoption, Adjustment	Foreign currency translation adjustments:	Benefit plan liability adjustment:	Retained earnings:	Retained earnings: Cumulative Effect, Period of Adoption, Adjusted Balance	[1]	Retained earnings: Cumulative Effect, Period of Adoption, Adjustment	[1]
Stockholders’ equity, beginning of period at Dec. 31, 2018		$ 36	$ 41,716		$ (30,286)	$ (7)	$ (2)	$ 0	$ 4,577	$ (11,297)		$ 1,884,227		$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Change in unrealized gains (losses) during period	$ 96,954				100,951
Amortization						7
Other-than-temporary impairments, non-credit, net of tax							0
Change in shadow deferred policy acquisition costs						(4)	0
Disposals of previously impaired securities						0
Change in translation adjustments during period	524								524
Amortization of net prior service cost and net gain (loss), net of tax	(4,355)									(4,355)
Net earnings	131,616										$ 131,616
Stockholder dividends											(1,273)
Stockholders’ equity, end of period at Dec. 31, 2019	2,116,430	36	41,716	$ 60,108	70,665	(4)	(2)	2	5,101	(15,652)	2,014,570	2,014,570		(3,032)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Change in unrealized gains (losses) during period	352,561				348,076
Amortization						4
Other-than-temporary impairments, non-credit, net of tax							0
Change in shadow deferred policy acquisition costs						(2)	0
Disposals of previously impaired securities						2
Change in translation adjustments during period	14								15
Amortization of net prior service cost and net gain (loss), net of tax	(12,784)									(12,784)
Net earnings	92,312										92,312
Stockholder dividends											(1,273)
Stockholders’ equity, end of period at Dec. 31, 2020	2,539,750	36	41,716	395,421	418,741	0	0	$ 0	5,116	(28,436)	2,102,577	$ 2,102,577		$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Change in unrealized gains (losses) during period	(179,587)				(192,521)
Amortization						0
Other-than-temporary impairments, non-credit, net of tax							0
Change in shadow deferred policy acquisition costs						0	0
Disposals of previously impaired securities						0
Change in translation adjustments during period	(16)								(16)
Amortization of net prior service cost and net gain (loss), net of tax	13,069									13,069
Net earnings	180,681										180,681
Stockholder dividends											(1,272)
Stockholders’ equity, end of period at Dec. 31, 2021	$ 2,539,691	$ 36	$ 41,716	$ 215,953	$ 226,220	$ 0	$ 0		$ 5,100	$ (15,367)	$ 2,281,986

[1] The 2019 beginning balance was revised by $11.8 million.