Summary of Other Long Term Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Other Liabilities Noncurrent [Abstract]
Capital lease obligations	$ 7,947	$ 8,111
Accrued pension liabilities	3,853	5,957
Accrued contingent considerations	1,304	2,381
Other	2,037	2,264
Total	$ 15,141	$ 18,713