Notes Receivable, Net - Schedule of Notes Receivable (Details) $ in Thousands	Dec. 31, 2016 USD ($) debtinstrument	Dec. 31, 2015 USD ($)
Mortgage Loans on Real Estate [Line Items]
Number of instruments held | debtinstrument	15
Net carrying amount of notes receivable | $	$ 276,163	$ 147,188
Core Portfolio [Member]
Mortgage Loans on Real Estate [Line Items]
Number of instruments held | debtinstrument	10
Net carrying amount of notes receivable | $	$ 216,400	113,048
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]
Number of instruments held | debtinstrument	1
Net carrying amount of notes receivable | $	$ 31,007	30,234
Effective interest rate	2.50%
Fund III [Member]
Mortgage Loans on Real Estate [Line Items]
Number of instruments held | debtinstrument	1
Net carrying amount of notes receivable | $	$ 4,506	3,906
Effective interest rate	18.00%
Fund IV [Member]
Mortgage Loans on Real Estate [Line Items]
Number of instruments held | debtinstrument	3
Net carrying amount of notes receivable | $	$ 24,250	$ 0
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%