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Summary of Significant Accounting Policies - Additional Information (Detail) |  |  | 12 Months Ended
--- | --- | --- | ---
Dec. 31, 2014 USD ($) | Dec. 03, 2014 USD ($) | Dec. 31, 2016 USD ($) Segment | Dec. 31, 2015 USD ($)
Summary Of Significant Accounting Policies [Line Items] |  |  |  |
Number of operating segments | Segment |  |  | 2 |
Number of reporting segment | Segment |  |  | 1 |
Transfers between Levels 1, 2 and 3 |  |  | $ 0 | $ 0
Cash and cash equivalents, carrying amount | $ 58,527,000 |  | 31,908,000 | 30,915,000
Impairment of intangible assets |  |  | 200,000 | $ 310,000
Discount rate |  |  |  | 13.00%
Net Book Value |  |  |  | $ 200,000
IPO costs reclassified to additional paid-in capital |  | $ 3,900,000 |  | 377,000
Payments related to IPO |  |  | $ 377,000 |
Maximum percentage of recognition of tax benefits from uncertain tax positions |  |  | 50.00% |
IPO [Member] |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |
Payments related to IPO | 2,900,000 |  |  |
Remaining amount of IPO costs included in accounts payable | $ 1,000,000 |  |  |
IPR&D [Member] |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |
Impairment of intangible assets |  |  | $ 200,000 | 300,000
Net Book Value |  |  | 0 | 200,000
Quoted Prices in Active Markets (Level 1) [Member] |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |
Assets, fair value disclosure, recurring |  |  | 0 | 0
Liabilities, fair value disclosure, recurring |  |  | 0 | 0
Quoted Prices in Active Markets (Level 1) [Member] | Money Market Funds [Member] |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |
Cash and cash equivalents, fair value |  |  | 30,300,000 | 25,800,000
Significant Other Observable Inputs (Level 2) [Member] |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |
Assets, fair value disclosure, recurring |  |  | 0 | 0
Liabilities, fair value disclosure, recurring |  |  | 0 | 0
Significant Unobservable Inputs (Level 3) [Member] |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |
Assets, fair value disclosure, recurring |  |  | 0 | 0
Liabilities, fair value disclosure, recurring |  |  | $ 0 | $ 0

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