Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

Unrecognized cost of unvested options awarded to employees as compensation.

+ References

No definition available.

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Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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General descriptive information regarding an arrangement under which employees and directors receive: (a) awards of equity shares, equity share options, or other equity instruments; or (b) the entity incurs liabilities to them: (1) in amounts based, at least in part, on the price of the entity's shares or other equity instruments; or (2) that require or may require settlement by issuance of the entity's shares. Such an arrangement is usually provided to employees and directors to compensate them, provide performance incentives to them, and to attract or retain their services. May also include pertinent information particular to a plan that is not elsewhere specified in the taxonomy.

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

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5047-113901

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- Definition

Date the equity-based award expires, in CCYY-MM-DD format.

+ References

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- Definition

Agreed-upon price for the exchange of the underlying asset relating to the share-based payment award.

+ References

No definition available.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Gross number of share options (or share units) granted during the period.

+ References

No definition available.

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- Definition

Number of share instruments newly issued under a share-based compensation plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- Definition

Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

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- Definition

Fair value of options vested. Excludes equity instruments other than options, for example, but not limited to, share units, stock appreciation rights, restricted stock.

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- Definition

Weighted average grant-date fair value of options vested.

+ References

No definition available.

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- Definition

Purchase price of common stock expressed as a percentage of its fair value.

+ References

No definition available.

+ Details

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Stock-Based Compensation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2008
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option grant, description		Options granted may be either incentive stock options or nonstatutory stock options.
Grant date fair value of options vested, per share	$ 3.13	$ 0.42	$ 0.35
Grant date fair value of options vested	$ 390	$ 339	$ 72
Unrecognized compensation cost	$ 5,600	$ 682
Weighted average period for recognition of compensation costs	3 years 5 months	2 years 10 months 24 days
Options to purchase shares granted to employees	1,911,137	1,642,799	1,190,349
Two Thousand Eight Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option issued				38,059
Stock option issued, exercise price				$ 0.80
Stock option vesting period				3 years
Stock option expiration period				Sep. 30, 2014
Two Thousand Eight Stock Option Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration period of stock option plan		10 years
Two Thousand Eight Stock Option Plan [Member] \| Ten Percent Stockholder [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration period of stock option plan		5 years
Two Thousand Eight Stock Option Plan [Member] \| Minimum \| Ten Percent Stockholder [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price of fair value of common stock, percentage		110.00%
Two Thousand Eight Stock Option Plan [Member] \| Nonstatutory Options [Member] \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price of fair value of common stock, percentage		85.00%