Description of Business and Summary of Significant Accounting Policies - Assets and Liabilities Measured at Fair Value on a Recurring Basis using Significant Unobservable Inputs (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Contingent Liability for Accrued Earn-out Acquisition Consideration
Beginning balance	$ 0	$ 10,095
Gains included in earnings	0	(3,105)
Remeasurement against goodwill	2,560	0
Foreign currency translation adjustments	3	(537)
Business settlements	0	(6,453)
Ending balance	2,563	0
The amount of total (gains) losses for the period included in earnings or changes to net assets, attributable to changes in unrealized gains relating to assets or liabilities still held at period-end.	$ 0	$ (3,105)