Share-Based Payments - Summary of Stock Option Activity and Related Information (Detail)	3 Months Ended
Mar. 31, 2016 $ / shares shares
Shares
Outstanding at beginning of period \| shares	1,803,574
Granted \| shares	916,776
Exercised \| shares	(118,110)
Cancelled or forfeited \| shares	(181,436)
Outstanding at end of period \| shares	2,420,804
Exercisable at March 31, 2016 \| shares	860,693
Vested and expected to vest at March 31, 2016 \| shares	2,012,694
Weighted-Average Exercise Price
Outstanding at beginning of period (in USD per share) \| $ / shares	$ 6.28
Granted (in USD per share) \| $ / shares	0.28
Exercised (in USD per share) \| $ / shares	0.06
Cancelled or forfeited (in USD per share) \| $ / shares	2.85
Outstanding at end of period (in USD per share) \| $ / shares	4.57
Exercisable at end of period (in USD per share) \| $ / shares	5.88
Vested and expected to vest at end of period \| $ / shares	$ 5.14

The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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)(iii)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section 50
-Paragraph 2
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Gross number of share options (or share units) granted during the period.

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Number of options outstanding, including both vested and non-vested options.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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As of the balance sheet date, the number of shares into which fully vested and expected to vest stock options outstanding can be converted under the option plan.

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As of the balance sheet date, the weighted-average exercise price for outstanding stock options that are fully vested or expected to vest.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated.

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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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Number of share options (or share units) exercised during the current period.

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