Notes Receivable, Net - Schedule of Notes Receivable (Details) $ in Thousands	Mar. 31, 2017 USD ($) debtinstrument	Dec. 31, 2016 USD ($)
Mortgage Loans on Real Estate [Line Items]
Net carrying amount of notes receivable	$ 276,507	$ 276,163
Core Portfolio [Member]
Mortgage Loans on Real Estate [Line Items]
Net carrying amount of notes receivable	$ 216,400	216,400
Number of instruments held | debtinstrument	5
Core Portfolio [Member] | Minimum [Member]
Mortgage Loans on Real Estate [Line Items]
Effective interest rate	6.00%
Core Portfolio [Member] | Maximum [Member]
Mortgage Loans on Real Estate [Line Items]
Effective interest rate	9.00%
Fund II [Member]
Mortgage Loans on Real Estate [Line Items]
Net carrying amount of notes receivable	$ 31,201	31,007
Number of instruments held | debtinstrument	1
Effective interest rate	2.50%
Fund III [Member]
Mortgage Loans on Real Estate [Line Items]
Net carrying amount of notes receivable	$ 4,656	4,506
Number of instruments held | debtinstrument	1
Effective interest rate	18.00%
Fund IV [Member]
Mortgage Loans on Real Estate [Line Items]
Net carrying amount of notes receivable	$ 24,250	24,250
Number of instruments held | debtinstrument	2
Fund IV [Member] | Minimum [Member]
Mortgage Loans on Real Estate [Line Items]
Effective interest rate	6.00%
Fund IV [Member] | Maximum [Member]
Mortgage Loans on Real Estate [Line Items]
Effective interest rate	15.30%
Fair Value, Inputs, Level 3 [Member]
Mortgage Loans on Real Estate [Line Items]
Net carrying amount of notes receivable	$ 276,507	$ 276,163
Number of instruments held | debtinstrument	9