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Warrants and Derivative Liabilities - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		0 Months Ended	6 Months Ended	3 Months Ended		6 Months Ended		0 Months Ended		1 Months Ended	6 Months Ended	1 Months Ended		0 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013 Convertible Bond	Sep. 30, 2012 Convertible Bond	Sep. 30, 2013 Convertible Bond	Sep. 30, 2012 Convertible Bond	Sep. 30, 2013 Capital Ventures International	Sep. 30, 2012 Capital Ventures International	Sep. 30, 2013 Capital Ventures International	Sep. 30, 2012 Capital Ventures International	Oct. 09, 2013 Capital Ventures International Second Amendment	Sep. 30, 2013 Capital Ventures International Second Amendment Fourth Quarter 2013	Sep. 30, 2013 Hercules Technology Growth Capital	Sep. 30, 2012 Hercules Technology Growth Capital	Sep. 30, 2013 Hercules Technology Growth Capital	Sep. 30, 2012 Hercules Technology Growth Capital	Apr. 04, 2012 Senior Convertible Debt Capital Ventures International	Apr. 04, 2010 Senior Convertible Debt Capital Ventures International	Dec. 31, 2012 New Unsecured Senior Convertible Note Capital Ventures International	Sep. 30, 2013 New Unsecured Senior Convertible Note Capital Ventures International	Dec. 31, 2012 New Unsecured Senior Convertible Note Capital Ventures International Minimum	Dec. 31, 2012 New Unsecured Senior Convertible Note Capital Ventures International Maximum	Jun. 05, 2012 Senior Secured Term Loan Hercules Technology Growth Capital
Derivative [Line Items]
Number of shares received from warrants received to purchase common stock																			3,094,060						139,276
Warrant exercise, waiting period											6 months
Warrant exercise period											5 years
Exercise price													$ 2.61						$ 5.45						$ 3.59
Beneficial ownership limitation percentage																							4.99%	9.99%
Required notification period											61 days
Gain (loss) in change of fair value of derivative instruments and warrants	$ 886,000	$ 3,285,000	$ 1,355,000	$ 897,000	$ 300,000	$ 1,700,000	$ 300,000	$ 1,000,000	$ 500,000	$ 1,500,000	$ 900,000	$ 100,000			$ 100,000	$ 100,000	$ 100,000
Conversion price																				$ 4.85			$ 3.19	$ 4.85
Increase in derivative liability																					500,000	500,000
Convertible debt instrument redemption waiting period			1 year
Convertible debt instrument contractual term			30 months
Non-cash interest expense														$ 1,100,000

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Purchase commitment issuance of warrants shares of common stock.

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Warrant exercise period.

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- Definition

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 12

-Section 13

-Sentence Column A

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The price per share of the conversion feature embedded in the debt instrument.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 470

-SubTopic 20

-Section 50

-Paragraph 5

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6928298&loc=SL6031898-161870

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Amount of decrease in the fair value of derivatives recognized in the income statement.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4A

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5618551-113959



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