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Equity and Stock-based Compensation - Schedule of Warrants to Purchase Shares of Common Stock (Detail) | 12 Months Ended
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Dec. 31, 2017 $ / shares shares
Class Of Warrant Or Right [Line Items] |
Number of Shares | 4,430
Year of Issuance 2000 [Member] |
Class Of Warrant Or Right [Line Items] |
Year of Issuance | 2000
Number of Shares | 4,430
Exercise Price per Share | $ / shares | $ 15.00
Reason for Issuance | Issued in connection with lease agreement
Expiration Date | Five years after initial public offering or upon merger or sale of the Company’s assets, whichever occurs first

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