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Stock-Based Compensation - Additional Information (Detail) (USD $) | 3 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Dec. 31, 2013 | Dec. 31, 2012 | Sep. 30, 2013 | Sep. 30, 2012 | Sep. 30, 2011
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |
Shares reserve for issuance | 395,950 |  |  |  |
Options granted and outstanding to purchase | 3,423,490 |  | 3,419,285 | 1,910,794 | 729,096
Number of Options Outstanding, Granted | 105,000 |  | 1,509,166 | 1,229,500 |
Options granted outside of Equity Incentive plans | 105,000 |  |  |  |
Stock-based compensation expense | $ 521,138 | $ 395,674 |  |  |
Fair value of the options granted | 531,510 | 6,083 |  |  |
Intrinsic value of the options exercised | 314,858 | 554 |  |  |
Dividend yield | 0.00% |  |  |  |
Calando Pharmaceuticals Inc |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |
Fair value of the options granted | 0 | 0 |  |  |
Pre-tax compensation expense | 28,695 |  |  |  |
Weighted average period to recognize pre-tax compensation expense | 1 year 9 months 18 days |  |  |  |
Arrowhead |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |
Pre-tax compensation expense | $ 5,111,999 |  |  |  |
Weighted average period to recognize pre-tax compensation expense | 3 years |  |  |  |
2000 Stock Option Plan |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |
Shares reserve for issuance | 153,200 |  |  |  |
Options granted and outstanding to purchase | 152,900 |  |  |  |
2004 Equity Incentive Plan |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |
Shares reserve for issuance | 2,902,360 |  |  |  |
Options granted and outstanding to purchase | 2,874,640 |  |  |  |
Number of Options Outstanding, Granted | 0 |  |  |  |

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- Definition Share based compensation arrangement by share based payment award options grants in period fair value. + References No definition available. + Details
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- Definition Weighted average period to recognize pre-tax compensation expense. + References No definition available. + Details
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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://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5047-113901 Reference 2: http://www.xbrl.org/2003/role/presentationRef -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=27013229&loc=d3e301413-122809 Reference 3: http://www.xbrl.org/2003/role/presentationRef -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=6415400&loc=d3e5070-113901 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 14 -Section F + Details
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- Definition Aggregate number of common shares reserved for future issuance. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.29) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- Definition Net number of non-option equity instruments granted to participants. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iv)(1) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d)(2) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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