Leases - Lease Cost (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Lease cost
Total operating lease cost	$ 1,572	$ 1,298	$ 4,323	$ 3,795
Depreciation of leased assets	326	328	981	1,009
Interest on lease liabilities	1,269	1,296	3,822	3,898
Total finance lease cost	1,595	1,624	4,803	4,907
Total lease cost	3,167	2,922	9,126	8,702
Short-term lease and variable lease costs	600	300	1,400	800
Service
Lease cost
Total operating lease cost	790	601	2,074	1,776
Research and development
Lease cost
Total operating lease cost	114	137	366	347
Sales and marketing*
Lease cost
Total operating lease cost	414	347	1,169	1,024
General and administrative*
Lease cost
Total operating lease cost	$ 254	$ 213	$ 714	$ 648