Fair Value (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	$ 100	$ 100
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Forward exchange contracts, asset	100
Forward exchange contracts, liability		$ 600
Level 2 [Member] | Carrying Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long term debt	691,300
Level 2 [Member] | Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long term debt	$ 701,900