Leases - Lease Costs (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Lessee, Lease, Description [Line Items]
Finance lease cost, amortization	$ 2,711,000	$ 2,517,000
Finance lease cost, interest expense	363,000	333,000
Total lease cost	8,084,000	7,698,000
Cost of revenue
Lessee, Lease, Description [Line Items]
Operating lease cost	3,527,000	3,497,000
Cost of revenue | Operating Lease
Lessee, Lease, Description [Line Items]
Variable lease costs	700,000	700,000
Cost of revenue | Finance Lease
Lessee, Lease, Description [Line Items]
Variable lease costs	2,400,000	2,900,000
Selling, general and administrative expenses
Lessee, Lease, Description [Line Items]
Operating lease cost	1,483,000	1,351,000
Selling, general and administrative expenses | Operating Lease
Lessee, Lease, Description [Line Items]
Variable lease costs	300,000	200,000
Selling, general and administrative expenses | Finance Lease
Lessee, Lease, Description [Line Items]
Variable lease costs	$ 0	$ 0