Leases - Lease Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Lessee, Lease, Description [Line Items]
Total operating lease costs	$ 8,540	$ 4,900	$ 4,800
Cost of revenue
Lessee, Lease, Description [Line Items]
Total operating lease costs	740
Sales and Marketing
Lessee, Lease, Description [Line Items]
Total operating lease costs	1,741
Technology and development
Lessee, Lease, Description [Line Items]
Total operating lease costs	2,462
General and administrative
Lessee, Lease, Description [Line Items]
Total operating lease costs	$ 3,597