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Significant Accounting Policies - Additional Information (Detail) |  | 3 Months Ended | 6 Months Ended
--- | --- | --- | ---
Apr. 11, 2017 USD ($) $ / shares shares | Jun. 30, 2016 shares | Jun. 30, 2017 USD ($) Segment | Jun. 30, 2016 USD ($)
Accounting Policy [Line Items] |  |  |  |
Net proceeds from offering |  |  | $ 12,244,000 | $ 4,496,000
Number of operating segment | Segment |  |  | 1 |
Anti-dilutive securities excluded from computation of diluted net income per share | shares |  | 6,600,000 |  |
ASU 2016-09 [Member] |  |  |  |
Accounting Policy [Line Items] |  |  |  |
Retrospective increase in deferred tax assets for previously unrecognized excess tax benefits |  |  | $ 19,500,000 |
Increase in valuation allowance |  |  | 19,500,000 |
Net impact to accumulated deficit |  |  | $ 0 |
Follow-on Offering [Member] |  |  |  |
Accounting Policy [Line Items] |  |  |  |
Common stock shares sold | shares | 5,228,750 |  |  |
Public offering price | $ / shares | $ 22.95 |  |  |
Net proceeds from offering | $ 115,100,000 |  |  |
Underwriting discounts and commissions | 4,900,000 |  |  |
Offering expenses | $ 600,000 |  |  |

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- Definition Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257 + Details
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- 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. + References No definition available. + Details
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