Regulatory Investigation - Additional Information (Detail) (USD $)	6 Months Ended	12 Months Ended
	Jun. 30, 2013	Dec. 31, 1993 PartnershipUnit
Regulatory Investigation [Abstract]
Number of partnership relating to regulatory investigation		3
Estimated an aggregate recovery	$ 5,918,000	$ 3,000,000
Affiliates reflecting estimated receivable	3,000,000	3,000,000
Recovery of amounts previously written off	$ 1,229,000