Loan Payable - Summary of Changes in Carrying Value of Loan Payable (Detail) (USD $)	1 Months Ended	12 Months Ended
Apr. 30, 2013	Dec. 31, 2013
Debt Instrument [Line Items]
Loan proceeds		$ 13,820,264
Cash discount		(100,000)
Fair value of warrants issued		(387,576)
Initial carrying value		13,332,688
Repayment of principal		(620,215)
Accretion of discount		196,771
Carrying value of total loan payable at 12/31/2013 (current and non-current)		12,909,244
Carrying value of loan payable, current portion		3,664,370
Carrying value of loan payable, non-current portion		9,244,874
Carrying value of total loan payable at 12/31/2013 (current and non-current)		12,909,244
Silicon Valley Bank [Member]
Debt Instrument [Line Items]
Loan proceeds	9,900,000	10,000,000
Cash discount		(100,000)
Fair value of warrants issued		(387,576)
Initial carrying value		9,512,424
Repayment of principal		(620,215)
Accretion of discount		196,771
Carrying value of total loan payable at 12/31/2013 (current and non-current)		9,088,980
Carrying value of loan payable, current portion		3,664,370
Carrying value of loan payable, non-current portion		5,424,610
Carrying value of total loan payable at 12/31/2013 (current and non-current)		9,088,980
CIRM Loan Agreement [Member]
Debt Instrument [Line Items]
Loan proceeds		3,820,264
Cash discount
Fair value of warrants issued
Initial carrying value		3,820,264
Repayment of principal
Accretion of discount
Carrying value of total loan payable at 12/31/2013 (current and non-current)		3,820,264
Carrying value of loan payable, current portion
Carrying value of loan payable, non-current portion		3,820,264
Carrying value of total loan payable at 12/31/2013 (current and non-current)		$ 3,820,264

Accretion Of Debt Discount Net Carrying Amount

No definition available.

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- Definition

Fair value of warrants issued.

+ References

No definition available.

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- Definition

Long Term Debt Carrying Value

+ References

No definition available.

+ Details

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- Definition

Amount of the total principal payments made during the annual reporting period.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

+ Details

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- Definition

The amount of debt discount that was originally recognized at the issuance of the instrument that has yet to be amortized.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

-Paragraph 1A

-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28541-108399

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- Definition

Including the current and noncurrent portions, aggregate carrying value as of the balance sheet date of loans payable (with maturities initially due after one year or beyond the operating cycle if longer).

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.16)

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-Topic 944

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 20, 22

-Article 5

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- Definition

Carrying value as of the balance sheet date of portion of long-term loans payable due within one year or the operating cycle if longer.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 20

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-Name Accounting Standards Codification

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- Definition

Carrying value as of the balance sheet date of loans payable (with maturities initially due after one year or beyond the operating cycle if longer), excluding current portion.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

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-Name Accounting Standards Codification

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- Definition

Cash received from principal payments made on loans related to operating activities.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 25

-Subparagraph (c)

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