Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Jun. 08, 2018
Liabilities:
Contingent consideration on acquisition liability		$ 1,500	$ 1,500
Operating cash balances not included in fair value table	$ 26,929	18,988
Recurring
Assets:
Money market funds	27,235	28,671
Total assets	27,235	28,671
Liabilities:
Contingent consideration on acquisition liability	0	1,500
Total liabilities	0	1,500
Recurring | Level 1
Assets:
Money market funds	27,235	28,671
Total assets	27,235	28,671
Liabilities:
Contingent consideration on acquisition liability	0	0
Total liabilities	0	0
Recurring | Level 2
Assets:
Money market funds	0	0
Total assets	0	0
Liabilities:
Contingent consideration on acquisition liability	0	0
Total liabilities	0	0
Recurring | Level 3
Assets:
Money market funds	0	0
Total assets	0	0
Liabilities:
Contingent consideration on acquisition liability	0	1,500
Total liabilities	$ 0	$ 1,500