Accumulated Other Comprehensive Income (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($)
Accumulated Other Comprehensive Income
Period Start Balance	$ 124,060
Period End Balance	112,693
Amounts reclassified from AOCI	0
Unrealized Gain/(Loss) on Marketable Securities
Accumulated Other Comprehensive Income
Period Start Balance	(13)
Other comprehensive loss	19
Period End Balance	6
Foreign Currency Items
Accumulated Other Comprehensive Income
Period Start Balance	2,596
Period End Balance	2,596
Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income
Period Start Balance	2,583
Other comprehensive loss	19
Period End Balance	$ 2,602