Stockholders' Equity - Stock-Based Compensation Expense Related to Stock Options and RSUs (Detail) (USD $)	3 Months Ended		6 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense included in operating expenses	$ 871,120	$ 916,050	$ 1,685,181	$ 1,745,121
Sales and marketing [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense included in operating expenses	191,962	234,167	367,080	435,690
Research and development [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense included in operating expenses	159,563	192,939	296,970	377,827
General and administrative [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense included in operating expenses	$ 519,595	$ 488,944	$ 1,021,131	$ 931,604