Income (loss) from Continuing Operations before Income Taxes (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Schedule of Income Before Income Tax [Line Items]
Income from operations before taxes	$ 17,734,809	$ 38,728,109	$ 53,784,180	$ 21,271,146
United States
Schedule of Income Before Income Tax [Line Items]
Income from operations before taxes	(214,312)	(236,952)	(1,167,190)	(953,598)
Foreign
Schedule of Income Before Income Tax [Line Items]
Income from operations before taxes	$ 17,949,121	$ 38,965,061	$ 54,951,370	$ 22,224,744