Significant Transactions During the Third Quarter of 2016 and Subsequent Events (Details) $ in Millions	1 Months Ended
	Sep. 30, 2016 USD ($) apartment	May 31, 2016 apartment	Aug. 31, 2016 USD ($)
Preferred Equity Investment In Limited Liability Company [Member] | 624 Yale Apartments [Member]
Other Commitments [Line Items]
Other commitment			$ 11.6
Number of units acquired (in number of units) | apartment		228
Preferred stock, stated interest percentage		12.00%
Commitment, funded amount	$ 1.9
Loan Commitment In Limited Liability Company [Member]
Other Commitments [Line Items]
Other commitment	$ 26.3
Number of units acquired (in number of units) | apartment	216
Note receivable, interest rate (as a percent)	10.75%
Commitment, funded amount	$ 4.4