Pension and Other Postretirement Benefits - Level 3 Asset Rollforward (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets at Beginning of Year	$ 315,649	$ 144,241
Translation Difference	13,876	5,499
Fair Value of Plan Assets at End of Year	302,270	315,649
Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets at Beginning of Year	111,674	82,255
Purchases	4,909	4,791
Assets acquired in business combinations		16,101
Sales		(516)
Settlements	(2,027)	(1,730)
Realized Gains		0
Unrealized Gains	8,730	11,642
Translation Difference	10,047	(869)
Fair Value of Plan Assets at End of Year	133,333	111,674
Insurance Contract [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets at Beginning of Year	92,657	79,873
Purchases	3,902	3,762
Assets acquired in business combinations		129
Sales		0
Settlements	(2,027)	(1,730)
Realized Gains		0
Unrealized Gains	8,917	12,199
Translation Difference	9,471	(1,576)
Fair Value of Plan Assets at End of Year	112,920	92,657
Real Estate Fund [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets at Beginning of Year	9,581	2,382
Purchases	18	0
Assets acquired in business combinations		7,058
Sales		(238)
Settlements	0	0
Realized Gains		0
Unrealized Gains	(16)	403
Translation Difference	192	(24)
Fair Value of Plan Assets at End of Year	9,775	9,581
Other-alternative investments [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets at Beginning of Year	9,436	0
Purchases	989	1,029
Assets acquired in business combinations		8,914
Sales		(278)
Settlements	0	0
Realized Gains		0
Unrealized Gains	(171)	(960)
Translation Difference	384	731
Fair Value of Plan Assets at End of Year	$ 10,638	$ 9,436