Pension and Other Postretirement Benefits - Level 3 Asset Rollforward (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets at Beginning of Year	$ 150,586
Fair Value of Plan Assets at End of Year	144,241	$ 150,586
Fair Value Inputs Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets at Beginning of Year	84,520	74,819
Purchases	4,707	2,350
Settlements	(1,399)	(1,661)
Unrealized Gains	(1,723)	(1,237)
Translation Difference	(3,850)	10,249
Fair Value of Plan Assets at End of Year	82,255	84,520
Insurance Contract [Member] | Fair Value Inputs Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets at Beginning of Year	82,092	72,778
Purchases	4,707	2,350
Settlements	(1,399)	(1,661)
Unrealized Gains	(1,817)	(1,425)
Translation Difference	(3,710)	10,050
Fair Value of Plan Assets at End of Year	79,873	82,092
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	2,428	2,041
Purchases	0	0
Settlements	0	0
Unrealized Gains	94	188
Translation Difference	(140)	199
Fair Value of Plan Assets at End of Year	$ 2,382	$ 2,428