Leases - Components of Lease Expense (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($)
Leases [Abstract]
Operating lease expense	$ 3,704
Finance lease expense:
Amortization of assets	244
Interest on lease liabilities	15
Short-term lease expense	36
Variable lease expense	618
Total lease expense	$ 4,617