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Stock-Based Compensation - Additional Information (Detail) |  | 9 Months Ended
--- | --- | ---
Jun. 10, 2015 shares | Sep. 30, 2015 Period shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |
Aggregate number of shares of common stock reserved for future issuance |  | 21,700,000
Outstanding options and other stock based awards |  | 14,500,000
Employee Stock Purchase Plan |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |
Aggregate number of shares of common stock reserved for future issuance |  | 1,700,000
Increase in shares of common stock authorized for issuance | 1,500,000 |
Employee Stock Purchase Plan, offering period |  | 12 months
Number of purchase periods within each offering period | Period |  | 2
Stock-based compensation, option to be granted at percentage of fair value of common stock |  | 85.00%
2008 Equity Incentive Plan |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |
Aggregate number of shares of common stock reserved for future issuance |  | 7,200,000
Increase in shares of common stock authorized for issuance | 5,000,000 |

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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) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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