Allowance for Doubtful Accounts (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Allowance For Doubtful Accounts Receivable Rollforward
Balance at beginning of period	$ 4,778,915	$ 1,659,337
Reclassification (to) from contractual allowance	(832,384)	1,458,737
Provisions recognized as reduction in revenues	5,118,194	3,755,035
Write-offs, net of recoveries	(7,323,154)	(2,094,194)
Balance at end of period	$ 1,741,571	$ 4,778,915