Leases - Components of Lease Expense (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019
Leases [Abstract]
Operating lease cost	$ 1,858	$ 5,305
Amortization of right-of-use assets	92	252
Interest on lease liabilities	16	46
Total finance lease cost	108	298
Short-term lease cost	1,793	5,557
Total lease expense	$ 3,759	$ 11,160