Closing price of common stock.

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Percentage of shares grant to participants.

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- Definition

Share-based compensation arrangement by share-based payment award award vesting date.

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No definition available.

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Share based compensation arrangement by share based payment award equity instruments other than options performance shares payout range maximum.

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No definition available.

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Share based compensation arrangement by share based payment award equity instruments other than options performance shares payout range minimum.

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No definition available.

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- Definition

Unrecognized cost of unvested share-based compensation awards.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (i)
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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.

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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.

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-Publisher FASB
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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).

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-Subparagraph (c)(2)(iii)(1)
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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).

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- Definition

The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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-Publisher FASB
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-Paragraph 2
-Subparagraph (c)(2)(i)-(ii)
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- Definition

The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(iii)
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- Definition

The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

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-Publisher FASB
-Name Accounting Standards Codification
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- Definition

The risk-free interest rate assumption that is used in valuing an option on its own shares.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Subparagraph (f)(2)(iv)
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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.

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No definition available.

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- Definition

The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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- Definition

Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (d)(2)
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- Definition

Net number of share options (or share units) granted during the period.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
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-Paragraph 2
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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.

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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

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- Definition

Percentage of vesting of share-based compensation awards.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
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- Definition

Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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- Definition

Purchase price of common stock expressed as a percentage of its fair value.

+ References

No definition available.

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Stock-Based Compensation Plans - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended		12 Months Ended
	Apr. 01, 2017	Jan. 31, 2016	Jan. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares available for grant under the stock incentive plans				219,983
Exercise price for the shares of the Company's common stock				$ 40.08	$ 32.24	$ 36.46
Grant date fair value				$ 68,068
Fair value assumptions, Dividend yield rate				0.80%	1.00%	1.10%
Closing price of common stock				$ 201.75
Unrecognized compensation costs related to non-vested				$ 4,300
Weighted-average period over which cost is expected to be recognized				2 years 2 months 12 days
Pay-out ranges, Minimum				0.00%
Pay-out ranges, Maximum				150.00%
Restricted Stock and Performance Shares [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation costs related to non-vested				$ 18,600
Weighted-average period over which cost is expected to be recognized				1 year 8 months 12 days
Employees Stock Purchase Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Period vested for option grants						1 year
Number of non-option equity instruments granted during the period				1,034	1,190	0
Percentage of shares grant to participants						20.00%
Chief Executive Officer [Member] \| Incentive Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options Expiration Period			5 years 6 months
Exercise price for the shares of the Company's common stock			$ 88.25
Number of stock option equity instruments granted during the period			119,981
Grant date fair value			$ 2,000
Percentage of fair market value of the common stock on the grant date			125.00%
Fair value assumptions, Risk free interest rate			1.40%
Fair value assumptions, Volatility rate			27.30%
Fair value assumptions, Dividend yield rate			0.90%
Chief Executive Officer [Member] \| Performance Based Share [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Grant date fair value			$ 6,000
Fair value assumptions, Risk free interest rate			1.30%
Fair value assumptions, Volatility rate			27.30%
Fair value assumptions, Dividend yield rate			0.90%
Number of non-option equity instruments granted during the period			116,659
Share-based compensation arrangement by share-based payment award, equity instruments other than options, nonvested, number					24,240	92,419
Chief Executive Officer [Member] \| Share-based Compensation Award, Tranche One [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award award vesting date			Jan. 15, 2018
Chief Executive Officer [Member] \| Share-based Compensation Award, Tranche One [Member] \| Incentive Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, award vesting rights			33.33%
Chief Executive Officer [Member] \| Share-based Compensation Award, Tranche One [Member] \| Performance Based Share [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, award vesting rights			50.00%
Chief Executive Officer [Member] \| Share-based Compensation Award, Tranche Two [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, award vesting rights			50.00%
Share-based compensation arrangement by share-based payment award award vesting date			Jan. 15, 2019
Chief Executive Officer [Member] \| Share-based Compensation Award, Tranche Two [Member] \| Incentive Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, award vesting rights			33.33%
Chief Executive Officer [Member] \| Share-based Compensation Award, Tranche Three [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award award vesting date			Jan. 15, 2020
Chief Executive Officer [Member] \| Share-based Compensation Award, Tranche Three [Member] \| Incentive Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, award vesting rights			33.33%
Officers and Senior Managers [Member] \| Performance Based Share [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options Expiration Period	2 years	3 years
Pay-out ranges, Minimum	0.00%	0.00%
Pay-out ranges, Maximum	150.00%	150.00%
Number of non-option equity instruments granted during the period	9,367	33,509
Fair value per share on the grant date	$ 186.74	$ 103.30
Officers and Senior Managers [Member] \| Share-based Compensation Award, Tranche One [Member] \| Performance Based Share [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, award vesting rights	50.00%	50.00%
Share-based compensation arrangement by share-based payment award award vesting date	Apr. 01, 2020	Jan. 31, 2020
Officers and Senior Managers [Member] \| Share-based Compensation Award, Tranche Two [Member] \| Performance Based Share [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, award vesting rights	50.00%	50.00%
Share-based compensation arrangement by share-based payment award award vesting date	Apr. 01, 2021	Jan. 31, 2021
Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Period vested for option grants				3 years
Options Expiration Period				6 years
Minimum [Member] \| Restricted Stock and Performance Shares [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Period vested for option grants				3 years
Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Period vested for option grants				5 years
Options Expiration Period				10 years
Maximum [Member] \| Restricted Stock and Performance Shares [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Period vested for option grants				5 years