Commitments and Contingencies - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2015 USD ($)
Property, Plant and Equipment [Line Items]
Future funding commitments	$ 13,118,000
Additional capital calls funded	125,000,000
Ground Lease [Member]
Property, Plant and Equipment [Line Items]
Ground lease commitments, 2015	383,000
Ground lease commitments, 2016	1,592,000
Ground lease commitments, 2017	1,656,000
Ground lease commitments, 2018	1,791,000
Ground lease commitments, 2019	1,844,000
Ground lease commitments, Thereafter	$ 105,784,000
Expiration date	Jun. 01, 2053