Leases - Components of Lease Expense (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($)
Leases
Operating lease cost	$ 10,794
Short-term lease cost	791
Variable lease cost	2,646
Total lease costs	14,231
Sublease income	(2,339)
Total lease costs, net of sublease income	$ 11,892