Preferred Equity Investments - Additional Information (Details) - PGRESS Funds	Dec. 16, 2015 USD ($)
Investment Holdings [Line Items]
Preferred equity ownership percentage	20.00%
PGRESS-A [Member]
Investment Holdings [Line Items]
Preferred equity investment	$ 12,150,000
Prior to Acquisition [Member]
Investment Holdings [Line Items]
Preferred equity ownership percentage	5.40%