Deferred Revenue - Summary of Deferred Service Contract Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Change in Contract with Customer, Liability [Roll Forward]
Beginning balance	$ 11,403	$ 11,779	$ 11,237	$ 14,222
Add: Payments received	3,880	3,854	13,226	9,314
Less: Revenue	(2,576)	(762)	(4,851)	(2,342)
Less: Revenue recognized from beginning balance	(2,027)	(3,047)	(8,932)	(9,370)
Ending balance	$ 10,680	$ 11,824	$ 10,680	$ 11,824