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Summary of Stock Options Summarized by Exercise Price (Detail) - Incentive Stock Options - $ / shares | 3 Months Ended |
--- | --- | ---
Mar. 31, 2018 | Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |
Outstanding Weighted Average, Shares | 431,860 |
Outstanding Weighted Average, Remaining Life (Months) | 51 months |
Outstanding Weighted Average, Exercise Price | $ 9.19 | $ 9.38
Range One |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |
Exercise Price Per Share, Lower Range | $ 7.50 |
Outstanding Weighted Average, Shares | 249,050 |
Outstanding Weighted Average, Remaining Life (Months) | 32 months |
Outstanding Weighted Average, Exercise Price | $ 7.5 |
Range Two |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |
Exercise Price Per Share, Lower Range | 11.32 |
Exercise Price Per Share, Upper Range | $ 14.49 |
Outstanding Weighted Average, Shares | 182,810 |
Outstanding Weighted Average, Remaining Life (Months) | 77 months |
Outstanding Weighted Average, Exercise Price | $ 11.49 |

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- Definition Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(i) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 + Details
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- Definition The floor of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (g) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 + Details
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- Definition The number of shares reserved for issuance pertaining to the outstanding stock options as of the balance sheet date for all option plans in the customized range of exercise prices. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(i)-(ii) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 + Details
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- Definition The ceiling of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (g) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 + Details
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- Definition Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (e)(1) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 + Details
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