Leases - Components of Lease Expense (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019
Operating lease cost	$ 83,914	$ 164,984
Short-term lease cost	3,742	6,226
Amortization of right-of-use assets	3,805	9,913
Interest on lease liabilities	1,099	2,280
Total finance lease cost	4,904	12,193
Total lease costs	$ 92,560	$ 183,403