Accumulated Other Comprehensive Income (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2019 USD ($)
Accumulated Other Comprehensive Income
Period Start Balance	$ 124,060
Period End Balance	109,626
Amounts reclassified from AOCI	0
Unrealized Gain/(Loss) on Marketable Securities
Accumulated Other Comprehensive Income
Period Start Balance	(13)
Other comprehensive gain	55
Period End Balance	42
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 gain	55
Period End Balance	$ 2,638