Stockholders' Equity - Additional Information (Detail) (USD $)
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0 Months Ended | 3 Months Ended | 6 Months Ended | 3 Months Ended | 6 Months Ended | 3 Months Ended | 6 Months Ended | 12 Months Ended | 1 Months Ended | 3 Months Ended | 6 Months Ended | 3 Months Ended | 6 Months Ended | 6 Months Ended | ||||||||||||||||||||||
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Aug. 02, 2013
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Sep. 30, 2014
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Sep. 30, 2013
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Sep. 30, 2014
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Sep. 30, 2013
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Mar. 31, 2014
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Sep. 30, 2014
Research and development expense [Member]
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Sep. 30, 2013
Research and development expense [Member]
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Sep. 30, 2014
Research and development expense [Member]
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Sep. 30, 2013
Research and development expense [Member]
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Sep. 30, 2014
General and administrative expense [Member]
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Sep. 30, 2013
General and administrative expense [Member]
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Sep. 30, 2014
General and administrative expense [Member]
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Sep. 30, 2013
General and administrative expense [Member]
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Sep. 30, 2014
Equity Distribution Agreement [Member]
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Mar. 31, 2014
Equity Distribution Agreement [Member]
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Nov. 30, 2013
Equity Distribution Agreement [Member]
Maximum [Member]
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Sep. 30, 2014
Restricted stock units (RSUs) [Member]
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Sep. 30, 2013
Restricted stock units (RSUs) [Member]
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Sep. 30, 2014
Restricted stock units (RSUs) [Member]
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Sep. 30, 2013
Restricted stock units (RSUs) [Member]
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Sep. 30, 2014
Restricted stock units (RSUs) [Member]
Consultants [Member]
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Sep. 30, 2013
Restricted stock units (RSUs) [Member]
Consultants [Member]
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Sep. 30, 2014
Restricted stock [Member]
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Sep. 30, 2013
Restricted stock [Member]
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Sep. 30, 2014
Restricted stock [Member]
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Sep. 30, 2013
Restricted stock [Member]
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Sep. 30, 2014
Equity Incentive Plan 2008 [Member]
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Sep. 30, 2013
Equity Incentive Plan 2008 [Member]
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May 31, 2008
Equity Incentive Plan 2008 [Member]
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Aug. 02, 2013
Underwriting Agreement [Member]
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Jul. 17, 2013
Underwriting Agreement [Member]
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Aug. 02, 2013
Underwriting Agreement [Member]
Overallotment Option Exercised [Member]
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Sep. 30, 2014
Equity Incentive Plan 2012 [Member]
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Aug. 31, 2013
Equity Incentive Plan 2012 [Member]
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Jan. 31, 2012
Equity Incentive Plan 2012 [Member]
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Class of Stock [Line Items] | ||||||||||||||||||||||||||||||||||||
Shares authorized under shelf registration statement | 150,000,000 | 150,000,000 | 150,000,000 | 100,000,000 | ||||||||||||||||||||||||||||||||
Issuance of common stock | 80,404,648 | 80,404,648 | 78,113,639 | 10,350,000 | 1,350,000 | |||||||||||||||||||||||||||||||
Offering price per share | $ 4.50 | $ 4.23 | ||||||||||||||||||||||||||||||||||
Proceeds from issuance of common stock | $ 43,400,000 | |||||||||||||||||||||||||||||||||||
Underwriting discounts and commissions and other offering expenses | 3,200,000 | |||||||||||||||||||||||||||||||||||
Number of shares to be offered and sold in equity distribution agreement | 4,000,000 | |||||||||||||||||||||||||||||||||||
Issuance of common stock from stock options exercises, net, Shares | 28,224 | 7,300 | 88,746 | 7,300 | 2,197,768 | 334,412 | ||||||||||||||||||||||||||||||
Value of shares sold under equity distribution agreement | 16,100,000 | 3,500,000 | ||||||||||||||||||||||||||||||||||
Issuance of common stock from warrant exercises, net, Shares | 0 | 1,670,851 | 110,600 | 1,870,986 | ||||||||||||||||||||||||||||||||
Warrants exercised | 0 | 2,026,428 | 111,647 | 2,278,557 | ||||||||||||||||||||||||||||||||
Stock option exercised | 28,224 | 7,300 | 88,746 | 7,300 | ||||||||||||||||||||||||||||||||
Common shares authorized to be issued | 1,521,584 | 5,000,000 | 6,553,986 | |||||||||||||||||||||||||||||||||
Shares issued during the year | 0 | 0 | ||||||||||||||||||||||||||||||||||
Termination date of Equity Incentive Plan | Jul. 01, 2018 | |||||||||||||||||||||||||||||||||||
Shares available for issuance | 11,553,986 | |||||||||||||||||||||||||||||||||||
Termination period of Equity Incentive Plan | 10 years | |||||||||||||||||||||||||||||||||||
Restricted stock awards granted | 0 | 0 | 60,000 | |||||||||||||||||||||||||||||||||
Restricted stock surrendered | 103,804 | 160,540 | 106,105 | 163,083 | ||||||||||||||||||||||||||||||||
Restricted stock awards vested during the period | 196,250 | 190,000 | 296,250 | 196,250 | 302,500 | |||||||||||||||||||||||||||||||
Stock option granted with immediate vesting | 103,804 | 160,540 | 106,105 | 163,083 | ||||||||||||||||||||||||||||||||
Restricted stock awards issued to member of senior management | 200,000 | |||||||||||||||||||||||||||||||||||
Total employee stock-based compensation recorded as operating expenses | 4,000 | 4,000 | 8,000 | 8,000 | 130,000 | 127,000 | 259,000 | 525,000 | 134,000 | 131,000 | 267,000 | 533,000 | ||||||||||||||||||||||||
Unrecognized restricted stock-based compensation expense | $ 466,000 | $ 466,000 | ||||||||||||||||||||||||||||||||||
Total unrecognized compensation cost related, weighted average period | 1 year 7 days |