Leases - Summary of Revenue from Master Lease (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Property Subject to or Available for Operating Lease [Line Items]
Rental income	$ 35,839	$ 42,185	$ 72,918	$ 91,359
Total revenue	49,270	57,893	103,047	123,291
Master Lease [Member]
Property Subject to or Available for Operating Lease [Line Items]
Rental income	22,605	29,208	45,136	60,859
Termination fee income		628	174	6,765
Tenant reimbursements	10,950	13,025	24,218	27,731
Total revenue	$ 33,555	$ 42,861	$ 69,528	$ 95,355