Service Providers And Related Party Agreements (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Related Party Transaction [Line Items]
Management Fees	$ 4,303,084	$ 6,422,717	$ 12,383,841	$ 20,990,965
Management Fees payable	2,891,036		2,891,036		1,523,526
Brokerage fees	301,492	408,982	1,153,576	1,782,401
Brokerage fees payable	$ 70		$ 70		$ 3,761