Restructuring Charges (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2017 USD ($)
Restructuring Charges
Balance at the beginning of the period	$ 3,157
Balance at the end of the period	234
Employee separation and related costs | Restructuring Plan 2016
Restructuring Charges
Balance at the beginning of the period	3,157
Utilized - cash	(2,925)
Accrual adjustment	(18)
Currency translation	20
Balance at the end of the period	$ 234