Real Estate Fund Investments - Summary of Ownership Interest in Property Funds and Property Funds Ownership Interest in Underlying Properties (Parenthetical) (Details)		12 Months Ended
	Jan. 24, 2017	Dec. 31, 2016
One Market Plaza [Member]
Investment Holdings [Line Items]
Ownership interest rate of property		49.00%
One Market Plaza [Member] | Other Investors [Member]
Investment Holdings [Line Items]
Ownership interest rate of property		49.00%
Subsequent Event [Member] | 60 Wall Street [Member]
Investment Holdings [Line Items]
Ownership interest rate of property	5.20%