Leases - Components of Lease Expense (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019
Finance lease expense:
Amortization of right-of-use assets	$ 16	$ 65
Interest on lease liabilities	0	1
Operating lease expense	1,657	4,906
Short-term lease expense	183	651
Variable lease expense	72	126
Total lease expense	$ 1,928	$ 5,749