Description of Business and Summary of Significant Accounting Policies - Contract Liabilities (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Accounting Policies [Abstract]
Deferred revenue included in accounts receivables	$ 7,700	$ 7,200
Change in Contract Liabilities
Balance, beginning of period	40,930	37,253
Revenue recognized from beginning balance	(26,400)	(32,783)
Additions, net of revenue recognized and currency translation	25,872	36,460
Balance, end of period	$ 40,402	$ 40,930