Share-Based Compensation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions |
3 Months Ended | 12 Months Ended | |
|---|---|---|---|
Mar. 31, 2018 |
Mar. 31, 2017 |
Dec. 31, 2017 |
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |||
| Share-based compensation expense | $ 9.8 | $ 11.3 | |
| Unrecognized compensation cost on non-vested stock awards | $ 80.9 | ||
| Unrecognized compensation cost on non-vested stock awards, weighted-average period of recognition | 1 year 4 months 24 days | ||
| Weighted-average grant date fair value of SARs granted | $ 86.30 | ||
| Total vesting date fair value of stock units | $ 0.1 | $ 0.1 | |
| SARs [Member] | |||
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |||
| SARs granted | 0 | ||
| Weighted-average grant date fair value of SARs granted | $ 28.32 | ||
| Total intrinsic value of awards exercised for SARs | $ 122.2 | $ 16.8 | |
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- Definition Intrinsic value of awards exercised for stock appreciation rights. No definition available.
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- Definition Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Unrecognized cost of unvested share-based compensation awards. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition The weighted average fair value at grant date for nonvested equity-based awards issued 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). Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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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. No definition available.
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- Definition Net number of non-option equity instruments granted to participants. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Details
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