Leases - Cost (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019
Lessee, Lease, Description [Line Items]
Total lease cost	$ 20,939	$ 42,543
Vehicle Rents and General and Other Operating [Member]
Lessee, Lease, Description [Line Items]
Operating lease cost	19,072	39,239
Depreciation and Amortization [Member]
Lessee, Lease, Description [Line Items]
Amortization of finance lease assets	797	1,605
Interest Expense [Member]
Lessee, Lease, Description [Line Items]
Interest on lease liabilities	278	596
General and Other Operating [Member]
Lessee, Lease, Description [Line Items]
Short-term lease cost	$ 792	$ 1,103