Investments in Unconsolidated Ventures - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended			3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013	Jun. 30, 2014 Invesco Mortgage Recovery Feeder Fund, L.P. And Invesco Mortgage Recovery Loans AIV, L.P.	Jun. 30, 2013 Invesco Mortgage Recovery Feeder Fund, L.P. And Invesco Mortgage Recovery Loans AIV, L.P.	Jun. 30, 2014 Invesco Mortgage Recovery Feeder Fund, L.P. And Invesco Mortgage Recovery Loans AIV, L.P.	Jun. 30, 2013 Invesco Mortgage Recovery Feeder Fund, L.P. And Invesco Mortgage Recovery Loans AIV, L.P.	Jun. 30, 2014 IMRF Loan Portfolio Member LLC	Jun. 30, 2013 IMRF Loan Portfolio Member LLC	Jun. 30, 2014 IMRF Loan Portfolio Member LLC	Jun. 30, 2013 IMRF Loan Portfolio Member LLC	Sep. 30, 2011 IMRF Loan Portfolio Member LLC
Schedule of Equity Method Investments [Line Items]
Initial investment in unconsolidated ventures						$ 100,000,000		$ 100,000,000
Total investments in unconsolidated ventures, at fair value	44,030,000		44,030,000		44,403,000	94,600,000		94,600,000						16,900,000
Committed to fund						5,400,000		5,400,000
Equity in earnings	3,894,000	2,157,000	4,335,000	3,747,000		(1,900,000)	561,000	2,100,000	906,000	1,600,000	197,000	1,700,000	92,000
Unrealized gain (loss) on investments						$ 1,300,000	$ 1,300,000	$ 1,400,000	$ 1,500,000	$ (959,000)	$ 84,000	$ (919,000)	$ 1,300,000