Leases - Components of Lease Expense (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019
Leases [Abstract]
Operating lease cost	$ 44,798	$ 90,514
Finance lease cost
Amortization of leased assets	1,492	2,638
Interest on leased assets	856	1,477
Short-term lease costs	1,313	1,990
Variable lease costs	2,725	6,573
Sublease income	(1,252)	(2,211)
Total lease cost	$ 49,932	$ 100,981