Income from Continuing Operations before Income Taxes (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Schedule of Income Before Income Tax [Line Items]
Income from operations before taxes	$ 15,227,596	$ 11,382,676	$ 28,079,903	$ 34,542,173
United States
Schedule of Income Before Income Tax [Line Items]
Income from operations before taxes	(669,423)	(521,809)	(1,821,093)	(2,099,653)
Foreign
Schedule of Income Before Income Tax [Line Items]
Income from operations before taxes	$ 15,897,019	$ 14,134,604	$ 29,900,996	$ 24,737,341