Summary of Significant Accounting Policies - Additional Information (Detail)
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12 Months Ended |
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Dec. 31, 2016
USD ($)
Financial_Institution
Segments
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Dec. 31, 2015
USD ($)
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Dec. 31, 2014 |
Jan. 01, 2017
USD ($)
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| Summary Of Significant Accounting Policies [Line Items] |
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| Royalty revenue |
$ 0
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| Prepaid R&D expense |
$ 1,256,000
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$ 1,500,000
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| Expected dividend yield |
0.00%
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0.00%
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0.00%
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| Number of operating segments | Segments |
1
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| ASU 2016-09 [Member] | Subsequent Event [Member] |
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| Summary Of Significant Accounting Policies [Line Items] |
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| Cumulative-effect adjustment in equity |
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$ 45,000
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| Cash And Cash Equivalents And Marketable Securities [Member] |
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| Summary Of Significant Accounting Policies [Line Items] |
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| Number of financial institutions | Financial_Institution |
3
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| Nonemployee Options [Member] |
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| Summary Of Significant Accounting Policies [Line Items] |
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| Expected life of options (in years) |
10 years
|
10 years
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10 years
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| Nonemployee Options [Member] | Maximum [Member] |
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| Summary Of Significant Accounting Policies [Line Items] |
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| Expected life of options (in years) |
10 years
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| Employee Options [Member] |
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| Summary Of Significant Accounting Policies [Line Items] |
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| Expected life of options (in years) |
6 years 3 months
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