Leases - NECG Lease Restructuring - Additional Information (Detail) - NECG Holdings Corp [Member] - Property		9 Months Ended
	Dec. 31, 2015	Sep. 30, 2016	May 01, 2012
Leases [Line Items]
Number of properties formerly leased			84
Number of leased properties remaining in NECG lease	8
Number of leased properties removed		5
Number of properties still in lease that will be removed once re-positioning of tenant is complete		3