Subsequent Events (Details) - USD ($)			9 Months Ended
	Oct. 13, 2017	Oct. 03, 2017	Sep. 30, 2017	Sep. 30, 2016	Oct. 31, 2017	Oct. 25, 2017	Oct. 20, 2017
Subsequent Event [Line Items]
Proceeds from the disposition of properties			$ 47,025,000	$ 150,379,000
Mortgages
Subsequent Event [Line Items]
Borrowings, amount			$ 128,300,000.0
Subsequent Event | Fund V
Subsequent Event [Line Items]
Capital called						$ 45,800,000
Condominium Tower I Property | Subsequent Event | Fund II | Disposed of by sale
Subsequent Event [Line Items]
Proceeds from the disposition of properties	$ 96,000,000
Repayments of debt	81,000,000
Cost of real estate sales	$ 15,000,000
301 W. Broughton, 101-103 W. Broughton and 125 E. Broughton properties | Subsequent Event | Fund IV | Disposed of by sale
Subsequent Event [Line Items]
Proceeds from the disposition of properties		$ 9,500,000
Hickory Ridge - Hickory, NC | Subsequent Event | Mortgages | Fund V
Subsequent Event [Line Items]
Borrowings, amount							$ 28,600,000.0
Bridge facility | Subsequent Event | Fund IV
Subsequent Event [Line Items]
Maximum borrowing capacity					$ 41,800,000.0
Operating Partnership | Subsequent Event | Fund V
Subsequent Event [Line Items]
Capital called						$ 9,200,000