Leases - Components of Lease Expense (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($)
Finance lease expense:
Amortization of right-of-use assets	$ 33
Interest on lease liabilities	1
Operating lease expense	1,644
Short-term lease expense	224
Variable lease expense	36
Total lease expense	$ 1,938