Stock-Based Compensation Stock Reserved for Future Issuance (Details) - shares |
Dec. 31, 2017 |
Dec. 31, 2016 |
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| Equity Incentive Plan [Member] | ||
| Class of Stock [Line Items] | ||
| Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant | 11,956,531 | |
| ESPP [Member] | ||
| Class of Stock [Line Items] | ||
| Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant | 1,714,141 | |
| Restricted Stock Unit and Restricted Stock Award [Member] | ||
| Class of Stock [Line Items] | ||
| Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number | 3,183,000 | 3,670,000 |
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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. No definition available.
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- Definition Number of equity instruments other than options outstanding, including both vested and non-vested instruments. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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