Operating Leases - Components of Lease Costs (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019
Leases [Abstract]
Operating lease costs	$ 2,665	$ 7,713
Short-term and variable lease costs	1,196	3,364
Lease costs	$ 3,861	$ 11,077