Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
After Tax components of accumulated comprehensive loss [Abstract]
Foreign currency translation adjustment	$ (21,140)	$ (27,839)
Unrecognized pension and post-retirement benefit cost, net of tax of $2,192 and $2,261, respectively	(3,103)	(3,723)
Accumulated other comprehensive loss	(24,243)	(31,562)
Unrecognized pension and post-retirement benefit cost, tax	$ 2,192	$ 2,261