Leases - Narrative (Details) - USD ($)	3 Months Ended			9 Months Ended		12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Lessee, Lease, Description [Line Items]
Operating leases renewal terms (up to)	5 years			5 years
Finance leases renewal terms (up to)	5 years			5 years
Lessor, Lease, Description [Line Items]
Customers' right to purchase leased system, term		12 months
Sales-type lease, revenue	$ 0		$ 0	$ 0	$ 0	$ 700,000
Proceeds from customer's exercise of purchase option	$ 100,000			300,000
Revenue from equipment leases				$ 100,000
Minimum
Lessee, Lease, Description [Line Items]
Remaining lease terms of operating leases	1 year			1 year
Remaining lease terms of finance leases	1 year			1 year
Maximum
Lessee, Lease, Description [Line Items]
Remaining lease terms of operating leases	10 years			10 years
Other Current Assets
Lessor, Lease, Description [Line Items]
Sales-type lease receivable	$ 400,000	$ 700,000		$ 400,000		$ 700,000