Organization and Principal Activities - Additional Information (Details) $ in Thousands |
3 Months Ended | |
|---|---|---|
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Mar. 31, 2019
USD ($)
Segment
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Dec. 31, 2018
USD ($)
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| Organization Consolidation And Presentation Of Financial Statements [Line Items] | ||
| Date of incorporation | Apr. 21, 2003 | |
| Headquartered in state, country name | South San Francisco, California | |
| Number of operating segments | Segment | 1 | |
| Accumulated deficit | $ 154,251 | $ 150,328 |
| Unrestricted cash, cash equivalents and marketable securities | $ 184,300 | |
| Substantial doubt about going concern, within one year | false | |
| Minimum | ||
| Organization Consolidation And Presentation Of Financial Statements [Line Items] | ||
| Going concern period from issuance date of unaudited interim condensed financial statements | 1 year |
| X | ||||||||||
- Definition Date when an entity was incorporated No definition available.
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- Definition State or Country Name where an entity is incorporated No definition available.
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| X | ||||||||||
- Definition Going concern period from issuance of unaudited interim condensed financial statements. No definition available.
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| X | ||||||||||
- Definition Organization consolidation and presentation of financial statements line items. No definition available.
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| X | ||||||||||
- Definition Unrestricted cash, cash equivalents and marketable securities at carrying value. No definition available.
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| X | ||||||||||
- Definition Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues. No definition available.
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| X | ||||||||||
- Definition The cumulative amount of the reporting entity's undistributed earnings or deficit. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- Definition Indicates (true false) whether there was substantial doubt about ability to continue as going concern within one year after date financial statements are issued. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- Details
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