Leases - Net Lease Expense (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019
Net lease expense
Operating lease expense	$ 2,340	$ 4,655
Short-term lease expense	77	275
Variable lease expense	329	1,046
Amortization of right-of-use assets	1	1
Interest on lease liabilities		1
Total finance lease expense	1	2
Less: Sublease income	(249)	(498)
Net lease expense	$ 2,498	$ 5,480