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Shared-Based Compensation - Additional Information (Detail) $ / shares in Units, $ in Millions | 3 Months Ended | 6 Months Ended
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Jun. 30, 2018 $ / shares shares | Jun. 30, 2018 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |
Number of options granted | 55,300 | 55,300
Weighted average grant date fair value of the options granted | $ / shares |  | $ 10.68
Total grant-date fair value of restricted stock | $ |  | $ 1.8
Restricted Stock [Member] |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |
Stock units issued |  | 86,516
Fair value assumptions, exercise price | $ / shares | $ 24.55 | $ 24.55
TSR Awards [Member] |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |
Stock units issued |  | 55,000
Percentage of shares issuable based on threshold performance |  | 50.00%
Percentage of shares issuable based on target performance |  | 100.00%
Percentage of shares issuable based on maximum performance |  | 150.00%
ROIC Awards [Member] |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |
Stock units issued |  | 55,000
Percentage of shares issuable based on threshold performance |  | 35.00%
Percentage of shares issuable based on target performance |  | 100.00%
Percentage of shares issuable based on maximum performance |  | 150.00%
Officers and Key Employees [Member] | Restricted Stock [Member] |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |
Stock awards granted vesting period |  | 3 years
Non-executive Directors [Member] | Restricted Stock [Member] |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |
Stock awards granted vesting period |  | 1 year

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- Definition Share based compensation arrangement by share-based payment award percentage of shares issuable based on maximum performance. + References No definition available. + Details
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- Definition Share based compensation arrangement by share-based payment award, percentage of shares Issuable based on target performance. + References No definition available. + Details
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- Definition Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, 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 (a)(1) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 + Details
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- Definition The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target 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)(2)(iii)(1) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 + Details
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- Definition Agreed-upon price for the exchange of the underlying asset relating to the share-based payment award. + References No definition available. + Details
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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- Definition Net number of share options (or share units) granted during the period. + 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)(iv)(1) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 + Details
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- Definition The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology. + 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 (d)(1) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 + Details
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- Definition Fair value of options vested. Excludes equity instruments other than options, for example, but not limited to, share units, stock appreciation rights, restricted stock. + 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) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 + Details
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