Subsequent Events - Additional Information (Details) - USD ($) $ in Thousands			6 Months Ended
	Jul. 24, 2019	Jul. 15, 2019	Jun. 30, 2019	Jun. 30, 2018
Subsequent Event [Line Items]
Mortgages paid			$ 122,492	$ 48,272
Fund III
Subsequent Event [Line Items]
Capital called			426,300
Fund IV
Subsequent Event [Line Items]
Capital called			425,400
Fund V
Subsequent Event [Line Items]
Capital called			$ 118,300
Subsequent Event
Subsequent Event [Line Items]
Capital called	$ 17,000
Repayments of debt obligations	4,300
Subsequent Event | Fund IV
Subsequent Event [Line Items]
Sale of property	7,800
Subsequent Event | Fund IV | Mortgages
Subsequent Event [Line Items]
Mortgages paid		$ 4,800
Subsequent Event | Fund III
Subsequent Event [Line Items]
Capital called	10,100
Subsequent Event | Fund IV
Subsequent Event [Line Items]
Capital called	12,700
Subsequent Event | Fund V
Subsequent Event [Line Items]
Capital called	$ 57,800