Real Estate and Loans Receivable - Summary of Loans (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Loans [Line Items]
Loans, Balance	$ 1,928,524	$ 1,216,121
Mortgage Loans [Member]
Loans [Line Items]
Loans, Balance	$ 1,778,316	$ 1,060,400
Loans, Weighted Average Interest Rate	8.30%	8.80%
Acquisition Loans [Member]
Loans [Line Items]
Loans, Balance	$ 118,448	$ 121,464
Loans, Weighted Average Interest Rate	13.80%	13.70%
Working Capital and Other Loans [Member]
Loans [Line Items]
Loans, Balance	$ 31,760	$ 34,257
Loans, Weighted Average Interest Rate	7.60%	9.00%