Loans Receivable - Activity Related to Loans Receivable (Parenthetical) (Detail) - USD ($)	Jun. 30, 2016	Apr. 13, 2016	Dec. 31, 2015	Jun. 30, 2015	Dec. 31, 2014
Mortgage Loans on Real Estate [Line Items]
Loans receivable, net	$ 14,304,000		$ 5,280,000	$ 8,395,000	$ 24,005,000
446 High Line LLC [Member]
Mortgage Loans on Real Estate [Line Items]
Loans receivable, net		$ 3,175,000
Short term loan	635,000	$ 635,000
Jacksonville, Florida [Member]
Mortgage Loans on Real Estate [Line Items]
Loans receivable, net	$ 8,400,000