Leases - Lease Cost (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019
Lease cost
Total operating lease cost	$ 1,177	$ 3,609
Depreciation of leased assets	332	997
Interest on lease liabilities	1,308	3,849
Total finance lease cost	1,640	4,846
Total lease cost	2,817	8,455
Short-term lease and variable lease costs	200	600
Service
Lease cost
Total operating lease cost	552	1,732
Research and development
Lease cost
Total operating lease cost	80	232
Sales and marketing
Lease cost
Total operating lease cost	338	1,037
General & administrative
Lease cost
Total operating lease cost	$ 207	$ 608