Equity Investments - Additional Information (Detail)					1 Months Ended		3 Months Ended	6 Months Ended
	Jul. 01, 2015 USD ($)	Jun. 25, 2015 USD ($) Assets SecurityLoan	Jun. 01, 2015 USD ($)	Jan. 02, 2015 USD ($)	May. 31, 2015 USD ($)	Apr. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)
Schedule of Equity Method Investments [Line Items]
Proceeds from sale of interest in joint venture			$ 82,471,000						$ 200,000
Distributions received								$ 4,959,000	$ 673,000
Vintage Housing Holdings [Member]
Schedule of Equity Method Investments [Line Items]
Additional contribution in equity investments				$ 5,645,000
Liquidation value of investment										$ 82,928,000
Concord Debt Holdings LLC [Member]
Schedule of Equity Method Investments [Line Items]
Distributions received					$ 20,173,000
701 Seventh WRT Investor LLC [Member]
Schedule of Equity Method Investments [Line Items]
Additional capital contributions						$ 673,000	$ 1,529,000
Capital contributions								108,825,000
Aggregate committed capital investment amount								$ 125,000,000
CDH CDO LLC [Member]
Schedule of Equity Method Investments [Line Items]
Proceeds from sale of interest in joint venture		$ 54,122,000
Number of bond assets sold | Assets		4
Number of loan asset sold | SecurityLoan		1
CDH CDO LLC [Member] | Subsequent Event [Member]
Schedule of Equity Method Investments [Line Items]
Amount received from the venture	$ 6,200,000