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Stock-Based Compensation - Additional Information (Detail) - USD ($) | 12 Months Ended
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Sep. 30, 2018 | Sep. 30, 2017 | Sep. 30, 2016
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |
Number of Options Outstanding | 5,524,399 | 5,549,543 |
Number of Options Outstanding, Granted | 822,000 |  |
RSU awards vesting, description | At vesting, each outstanding RSU will be exchanged for one share of the Company’s Common Stock. RSU recipients may elect to net share settle upon vesting, in which case the Company pays the employee’s income taxes due upon vesting and withholds a number of shares of Common Stock of equal value. RSU awards generally vest subject to the satisfaction of service requirements or the satisfaction of both service requirements and achievement of certain performance targets. |  |
Employee Stock Option |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |
Stock-based compensation expense | $ 3,265,348 | $ 4,524,833 | $ 6,361,396
Grant date fair value of the options granted | 4,141,318 | 849,816 | 6,426,707
Intrinsic value of options exercised | 5,805,317 | 35,512 | 142,690
Unrecognized pre-tax compensation expense | $ 5,117,079 |  |
Weighted average period to recognize pre-tax compensation expense | 2 years 8 months 12 days |  |
Dividend yield | 0.00% |  |
Restricted Stock Units (RSUs) |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |
Number of restricted stock units outstanding, granted | 1,245,500 |  |
Stock-based compensation expense | $ 5,189,259 | $ 3,366,762 | $ 5,234,420
Weighted average period to recognize pre-tax compensation expense | 2 years 7 months 6 days |  |
Unrecognized pre-tax compensation expense | $ 2,451,889 |  |
2004 Equity Incentive Plan |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |
Shares reserve for issuance | 1,783,568 |  |
2004 Equity Incentive Plan | Employee Stock Option |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |
Number of Options Outstanding | 1,783,568 |  |
Number of Options Outstanding, Granted | 0 |  |
2004 Equity Incentive Plan | Restricted Stock Units (RSUs) |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |
Number of restricted stock units outstanding, granted | 0 |  |
2013 Incentive Plan |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |
Shares reserve for issuance | 6,262,690 |  |
2013 Incentive Plan | Employee Stock Option |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |
Number of Options Outstanding | 3,057,022 |  |
Number of Options Outstanding, Granted | 467,000 |  |
2013 Incentive Plan | Restricted Stock Units (RSUs) |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |
Number of restricted stock units outstanding | 2,965,999 |  |
Number of restricted stock units outstanding, granted | 1,243,000 |  |
Outside Of Equity Compensation Plans |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |
Shares reserve for issuance | 683,809 |  |
Outside Of Equity Compensation Plans | Employee Stock Option |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |
Number of Options Outstanding, Granted | 355,000 |  |
Outside Of Equity Compensation Plans | Restricted Stock Units (RSUs) |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |
Number of restricted stock units outstanding | 2,500 |  |
Number of restricted stock units outstanding, granted | 2,500 |  |

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- Definition Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5047-113901 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 14.F) -URI http://asc.fasb.org/extlink&oid=115993241&loc=d3e301413-122809 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(1)(i) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
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- Definition General descriptive information regarding an arrangement under which employees and directors receive: (a) awards of equity shares, equity share options, or other equity instruments; or (b) the entity incurs liabilities to them: (1) in amounts based, at least in part, on the price of the entity's shares or other equity instruments; or (2) that require or may require settlement by issuance of the entity's shares. Such an arrangement is usually provided to employees and directors to compensate them, provide performance incentives to them, and to attract or retain their services. May also include pertinent information particular to a plan that is not elsewhere specified in the taxonomy. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5047-113901 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
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