Real Estate Fund Investments - Schedule of Investments of Property Funds (Parenthetical) (Details)		6 Months Ended
	Jul. 10, 2015 USD ($) ft²	Jun. 30, 2015 USD ($) ft²
Investment Holdings [Line Items]
Area of office properties | ft²		10,400,000
One Market Plaza [Member]
Investment Holdings [Line Items]
Ownership interest rate of property		49.00%
Fund VII and VII-H [Member]
Investment Holdings [Line Items]
Committed capital that had not yet been invested		$ 57,600,000
Fund VII and VII-H [Member] | 670 Broadway [Member] | Subsequent Event [Member]
Investment Holdings [Line Items]
Area of office properties | ft²	77,480
Payment to acquire office building	$ 112,000,000
Other Investors [Member] | One Market Plaza [Member]
Investment Holdings [Line Items]
Ownership interest rate of property		49.00%