Investments in Unconsolidated Ventures - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended			3 Months Ended		9 Months Ended				3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011	Sep. 30, 2012 Invesco Mortgage Recovery Feeder Fund, L.P. And Invesco Mortgage Recovery Loans AIV, L.P.[Member]	Sep. 30, 2011 Invesco Mortgage Recovery Feeder Fund, L.P. And Invesco Mortgage Recovery Loans AIV, L.P.[Member]	Sep. 30, 2012 Invesco Mortgage Recovery Feeder Fund, L.P. And Invesco Mortgage Recovery Loans AIV, L.P.[Member]	Sep. 30, 2011 Invesco Mortgage Recovery Feeder Fund, L.P. And Invesco Mortgage Recovery Loans AIV, L.P.[Member]	Dec. 31, 2010 Invesco Mortgage Recovery Feeder Fund, L.P. And Invesco Mortgage Recovery Loans AIV, L.P.[Member]	Dec. 31, 2009 Invesco Mortgage Recovery Feeder Fund, L.P. And Invesco Mortgage Recovery Loans AIV, L.P.[Member]	Sep. 30, 2012 IMRF Loan Portfolio Member LLC [Member]	Sep. 30, 2011 IMRF Loan Portfolio Member LLC [Member]	Sep. 30, 2012 IMRF Loan Portfolio Member LLC [Member]	Sep. 30, 2011 IMRF Loan Portfolio Member LLC [Member]
Schedule Of Equity Method Investments Joint Ventures [Line Items]
Initial investment in unconsolidated ventures						$ 25,000,000		$ 25,000,000
Total investments in unconsolidated ventures, at fair value	55,654,000		55,654,000		68,793,000					100,000,000	100,000,000		16,900,000		16,900,000
Committed to fund						17,100,000		17,100,000
Equity in earnings	3,262,000	(993,000)	6,231,000	2,738,000		1,400,000	823,000	2,100,000	6,400,000			2,500,000		3,200,000
Unrealized gain (loss) from investments in unconsolidated ventures						464,000	1,800,000	774,000	3,700,000			191,000		116,000
Net income attributable to non-controlling interest	$ 1,026,000	$ 1,091,000	$ 3,025,000	$ 3,948,000									$ 0		$ 0