Fair Value Measurements - Assets and Liabilities Measured at Fair Value (Details) - Recurring - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Assets:
Total assets	$ 2,828	$ 2,871
Liabilities:
Total liabilities	2,372	2
Money market funds
Assets:
Money market funds	2,828	2,806
Contingent earn-out
Liabilities:
Contingent earn-out	2,372	0
Foreign currency derivative contracts
Assets:
Foreign currency derivative contracts	0	65
Liabilities:
Foreign currency derivative contracts	0	2
Level 1
Assets:
Total assets	2,828	2,806
Liabilities:
Total liabilities	0	0
Level 1 | Money market funds
Assets:
Money market funds	2,828	2,806
Level 1 | Contingent earn-out
Liabilities:
Contingent earn-out	0	0
Level 1 | Foreign currency derivative contracts
Assets:
Foreign currency derivative contracts	0	0
Liabilities:
Foreign currency derivative contracts	0	0
Level 2
Assets:
Total assets	0	65
Liabilities:
Total liabilities	0	2
Level 2 | Money market funds
Assets:
Money market funds	0	0
Level 2 | Contingent earn-out
Liabilities:
Contingent earn-out	0	0
Level 2 | Foreign currency derivative contracts
Assets:
Foreign currency derivative contracts	0	65
Liabilities:
Foreign currency derivative contracts	0	2
Level 3
Assets:
Total assets	0	0
Liabilities:
Total liabilities	2,372	0
Level 3 | Money market funds
Assets:
Money market funds	0	0
Level 3 | Contingent earn-out
Liabilities:
Contingent earn-out	2,372	0
Level 3 | Foreign currency derivative contracts
Assets:
Foreign currency derivative contracts	0	0
Liabilities:
Foreign currency derivative contracts	$ 0	$ 0