Allowance for Doubtful Accounts (Detail) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Allowance For Doubtful Accounts Receivable Rollforward
Balance at beginning of period	$ 1,741,571
Provisions recognized as reduction in revenues	421,024	361,517
Write-offs, net of recoveries	(1,387,622)
Balance at end of period	$ 774,973