Organization and Limited Liability Company matters - Additional Information (Detail) (USD $)	1 Months Ended		6 Months Ended
	Nov. 30, 2000	Jan. 13, 1999	Jun. 30, 2012	Dec. 31, 2011
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Public offering of Limited Liability Company Units		15,000,000
Public offering of Limited Liability Company Units, price per unit		$ 10
Sale of Limited Liability Company Units, number of units		120,000
Proceeds from sale of Limited Liability Company Units		$ 1,200,000
Contributions received	135,700,000
Contributions unit received	13,570,188
Contributions of capital	500
Capital investment	$ 100
Units issued			13,560,188	13,560,188
Units outstanding			13,560,188	13,560,188
Reinvestment period			6 years