Leases - Components of Lease Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Lease cost
Operating lease cost	$ 1,248		$ 3,478
Short-term lease cost	88		649
Variable lease cost	150		434
Total lease cost	$ 1,486		4,561
Lease expense		$ 1,000		$ 3,000
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows from operating leases			$ 3,605
Weighted-average remaining lease term — operating leases	6 years 4 months 24 days		6 years 4 months 24 days
Weighted-average discount rate — operating leases	4.80%		4.80%