Description of Business and Summary of Significant Accounting Policies - Costs to Obtain and Fulfill a Contract (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Accounting Policies [Abstract]
Capitalized contract costs, net, current	$ 502	$ 646
Capitalized contract costs, net, noncurrent	952	984
Deferred Contract Costs [Roll Forward]
Balance, beginning of period	1,630	1,897
Costs recognized from the beginning balance	(437)	(743)
Additions, net of costs recognized	261	476
Balance, end of period	$ 1,454	$ 1,630