Subsequent Events - Additional Information (Detail) - Subsequent Event [Member] - USD ($)	Apr. 28, 2016	Apr. 13, 2016	May. 03, 2016
Subsequent Event [Line Items]
Annual one-time payment members of the Board of Trustees			$ 7,500
Aggregate amount of consideration			$ 383,000
446 High Line LLC [Member]
Subsequent Event [Line Items]
Amount funded to the venture		$ 3,175,000
Capital contribution to to the venture		2,540,000
Cash Distribution [Member]
Subsequent Event [Line Items]
Date of declaration of distribution	Apr. 28, 2016
Distribution declared per share	$ 2.00
Date of distribution payable	May 17, 2016
Distribution declared, date of record	May 10, 2016
Serure CB High Line [Member]
Subsequent Event [Line Items]
Partner loan receivable		$ 635,000
Partner loan receivable, interest rate		12.00%
Partner loan receivable, due period		60 days