Pension and Other Postretirement Benefits - Level 3 Asset Rollforward (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets at Beginning of Year	$ 122,857
Fair Value of Plan Assets at End of Year	136,041	$ 122,857
Fair Value Inputs Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets at Beginning of Year	64,797	72,895
Purchases	2,584	2,890
Settlements	(1,350)	(1,239)
Unrealized Gains	12,061	(2,342)
Translation Difference	(3,273)	(7,407)
Fair Value of Plan Assets at End of Year	74,819	64,797
Insurance Contract [Member] | Fair Value Inputs Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets at Beginning of Year	62,409	72,417
Purchases	2,584	953
Settlements	(1,350)	(1,239)
Unrealized Gains	12,005	(2,402)
Translation Difference	(2,870)	(7,320)
Fair Value of Plan Assets at End of Year	72,778	62,409
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	2,388	478
Purchases	0	1,937
Unrealized Gains	56	60
Translation Difference	(403)	(87)
Fair Value of Plan Assets at End of Year	$ 2,041	$ 2,388