Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ (26,646)
Other comprehensive income (loss)	40,205	$ (19,855)	$ (30,704)
Ending Balance	13,559	(26,646)
Accounting Standards Update 2016-01 [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassifications of AFS investments out of AOCI			(1,801)
Pension and Other Post-Retirement Actuarial Items [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(68,020)	(58,291)	(69,041)
Other comprehensive income before reclassifications	(22,055)	(21,473)	5,617
Tax effect	5,288	5,219	(1,032)
Other comprehensive income before reclassifications, net of tax	(16,767)	(16,254)	4,585
Amounts reclassified out of AOCI	10,168	8,694	8,343
Tax effect	(2,456)	(2,169)	(2,178)
Amounts reclassified out of AOCI, net of tax	7,712	6,525	6,165
Other comprehensive income (loss)	(9,055)	(9,729)	10,750
Ending Balance	(77,075)	(68,020)	(58,291)
Pension and Other Post-Retirement Actuarial Items [Member] | Accounting Standards Update 2016-01 [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassifications of AFS investments out of AOCI			0
Currency Translation Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	41,374	51,500	92,954
Other comprehensive income before reclassifications	49,260	(10,126)	(41,454)
Tax effect	0	0	0
Other comprehensive income before reclassifications, net of tax	49,260	(10,126)	(41,454)
Amounts reclassified out of AOCI	0	0	0
Tax effect	0	0	0
Amounts reclassified out of AOCI, net of tax	0	0	0
Other comprehensive income (loss)	49,260	(10,126)	(41,454)
Ending Balance	90,634	41,374	51,500
Currency Translation Adjustment [Member] | Accounting Standards Update 2016-01 [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassifications of AFS investments out of AOCI			0
Unrealized Gain (Loss) on Available-for-Sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	0	0	1,801
Other comprehensive income before reclassifications	0	0	0
Tax effect	0	0	0
Other comprehensive income before reclassifications, net of tax	0	0	0
Amounts reclassified out of AOCI	0	0	0
Tax effect	0	0	0
Amounts reclassified out of AOCI, net of tax	0	0	0
Other comprehensive income (loss)	0	0	0
Ending Balance	0	0	0
Unrealized Gain (Loss) on Available-for-Sale Securities [Member] | Accounting Standards Update 2016-01 [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassifications of AFS investments out of AOCI			(1,801)
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(26,646)	(6,791)	25,714
Other comprehensive income before reclassifications	27,205	(31,599)	(35,837)
Tax effect	5,288	5,219	(1,032)
Other comprehensive income before reclassifications, net of tax	32,493	(26,380)	(36,869)
Amounts reclassified out of AOCI	10,168	8,694	8,343
Tax effect	(2,456)	(2,169)	(2,178)
Amounts reclassified out of AOCI, net of tax	7,712	6,525	6,165
Other comprehensive income (loss)	40,205	(19,855)	(30,704)
Ending Balance	$ 13,559	$ (26,646)	$ (6,791)