Leases - Components of Lease Expense (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019
Finance lease cost:
Amortization of leased assets	$ 2,153	$ 4,245
Interest on lease liabilities	1,166	2,169
Sublease income	(1,043)	(2,087)
Total	9,951	19,776
Property operating expenses
Operating lease cost:
Lease expense	7,267	14,679
General and administrative expenses
Operating lease cost:
Lease expense	$ 408	$ 770