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 expense	$ 3,671	$ 11,148
Finance lease expense:
Amortization of assets	244	733
Interest on lease liabilities	11	39
Short-term lease expense	89	223
Variable lease expense	681	2,101
Total lease expense	$ 4,696	$ 14,244