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.

Reference 1: 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)
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
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Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 14
-Section F

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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)
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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

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

+ References

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-Name Accounting Standards Codification
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Stock Option and Incentive Plans - Incentive Plans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Jan. 01, 2016	Dec. 31, 2013
Stock option
Stock option and incentive plans
Stock options outstanding	1,799,226	1,670,574		1,093,208
Total stock-based compensation expense	$ 2,108	$ 698
Stock option \| Research and development
Stock option and incentive plans
Total stock-based compensation expense	685	137
Stock option \| General and administrative
Stock option and incentive plans
Total stock-based compensation expense	$ 1,423	$ 561
2005 Plan
Stock option and incentive plans
Common stock reserved for issuance (in shares)	0
Stock options outstanding	549,287
2014 Plan
Stock option and incentive plans
Common stock reserved for issuance (in shares)	4,371		775,634
Stock options outstanding	1,249,939