Pension and Other Postretirement Benefits - Level 3 Asset Rollforward (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets at Beginning of Year	$ 144,241
Fair Value of Plan Assets at End of Year	315,649	$ 144,241
Fair Value Inputs Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets at Beginning of Year	82,255	84,520
Purchases	4,791	4,707
Assets acquired in business combinations	16,101
Sales	(516)
Settlements	(1,730)	(1,399)
Unrealized Gains	11,642	(1,723)
Translation Difference	(869)	(3,850)
Fair Value of Plan Assets at End of Year	111,674	82,255
Insurance Contract [Member] | Fair Value Inputs Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets at Beginning of Year	79,873	82,092
Purchases	3,762	4,707
Assets acquired in business combinations	129
Sales	0
Settlements	(1,730)	(1,399)
Unrealized Gains	12,199	(1,817)
Translation Difference	(1,576)	(3,710)
Fair Value of Plan Assets at End of Year	92,657	79,873
Real Estate Fund [Member] | Fair Value Inputs Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets at Beginning of Year	2,382	2,428
Purchases	0	0
Assets acquired in business combinations	7,058
Sales	(238)
Settlements	0	0
Unrealized Gains	403	94
Translation Difference	(24)	(140)
Fair Value of Plan Assets at End of Year	9,581	2,382
Other-alternative investments [Member] | Fair Value Inputs Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets at Beginning of Year	0	0
Purchases	1,029	0
Assets acquired in business combinations	8,914
Sales	(278)
Settlements	0	0
Unrealized Gains	(960)	0
Translation Difference	731	0
Fair Value of Plan Assets at End of Year	$ 9,436	$ 0