Leases - Lease Cost (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Lease cost
Total operating lease cost	$ 1,178	$ 1,226
Depreciation of leased assets	353	333
Interest on lease liabilities	1,303	1,230
Total finance lease cost	1,656	1,563
Total lease cost	2,834	2,789
Short-term lease and variable lease costs	200
Service
Lease cost
Total operating lease cost	550	597
Research and development
Lease cost
Total operating lease cost	81	66
Sales and marketing
Lease cost
Total operating lease cost	332	355
General & administrative
Lease cost
Total operating lease cost	$ 215	$ 208