Leases - Net Lease Expense (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($)
Net lease expense
Operating lease expense	$ 2,316
Short-term lease expense	185
Variable lease expense	223
Finance lease expense:
Amortization of right-of-use assets	1
Total finance lease expense	1
Less: Sublease income	(225)
Net lease expense	$ 2,500