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Stockholders' Equity (Details 2) - USD ($) $ in Thousands | 1 Months Ended | 3 Months Ended | 12 Months Ended |
--- | --- | --- | --- | ---
Mar. 31, 2016 | Jun. 30, 2014 | Mar. 31, 2015 | Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 | Mar. 18, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |
Allocated share base compensation |  |  |  | $ 12,815 | $ 9,280 | $ 7,035 |
2014 Employee Stock Purchase Plan |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |
Employe Stock Purchase Plan ESPP, Offering Duration, Maximum |  | 27 months |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Discount from Market Price, Offering Date |  | 85.00% |  |  |  |  |
Stock Issued During Period, Shares, Employee Stock Purchase Plans (in Shares) |  |  |  | 124,380 |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant (in Shares) |  |  |  | 1,875,620 |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized (in Shares) |  | 2,000,000 |  |  |  |  |
Allocated share base compensation |  |  |  | $ 400 |  |  |
The 2015 Equity Incentive Plan |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant (in Shares) |  |  |  | 5,400,000 |  |  | 5,300,296
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized (in Shares) |  |  |  | 5,000,000 |  |  |
Equity Incentive Plan, Term |  |  |  | 10 years |  |  |
Share Based Compensation Arrangement By Share Based Payment Award Potential Number of Additional Shares Authorized (in Shares) |  |  |  | 3,000,000 |  |  |
Share Based Compensation Arrangement by Share Based Payment Award Potential Annual Increase in Shares, Percentage |  |  |  | 2.50% |  |  |
The 2015 Equity Incentive Plan | Subsequent Event |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized | 1,129,962 |  |  |  |  |  |
The 2005 Plan |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |
Equity Incentive Plan, Term |  |  |  | 10 years |  |  |
Equity Incentive Plan Potential Increase In Shares |  |  | 2.00% |  |  |  |
Employee Consultant And Directors Stock Options |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |
Allocated share base compensation |  |  |  | $ 7,900 | 6,700 | 5,900 |
Restricted Stock Units (RSUs) |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |
Allocated share base compensation |  |  |  | $ 3,900 | $ 2,000 | $ 600 |

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- Definition 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. + References 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) -URI http://asc.fasb.org/extlink&oid=27013229&loc=d3e301413-122809 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5047-113901 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(1)(i) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 14 -Section F + Details
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