Stock-Based Compensation - Summary of Activity for RSUs under 2014 Plan (Detail)	9 Months Ended
Sep. 30, 2020 $ / shares shares
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
RSUs/SARs, beginning of period \| shares	1,102,534
Granted \| shares	305,610
Vested \| shares	(732,416)
Forfeited \| shares	(63,094)
RSUs/SARs, end of period \| shares	613,169
RSUs/SARs, Weighted Average Grant Date Fair Value, Beginning of period \| $ / shares	$ 85.93
Weighted Average Grant Date Fair Value, Granted \| $ / shares	98.25
Weighted Average Grant Date Fair Value, Vested \| $ / shares	85.32
Weighted Average Grant Date Fair Value, Forfeited \| $ / shares	85.40
RSUs/SARs, Weighted Average Grant Date Fair Value, end of period \| $ / shares	$ 92.87
Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Accrued dividend shares \| shares	535
Weighted Average Grant Date Fair Value, Accrued dividend shares \| $ / shares	$ 107.82

Share amount for share-based compensation arrangement by share-based payment award equity instruments accrued dividend.

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- Definition

Per share amount share based compensation arrangement by share based payment award equity instruments other than options accrued dividend equivalents weighted average grant date fair value.

+ References

No definition available.

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- Definition

The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(3)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

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- Definition

Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
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-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

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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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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
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-Paragraph 2
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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).

+ References

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-Publisher FASB
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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.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
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Per share or unit weighted-average fair value of nonvested award under share-based payment arrangement. Excludes share and unit options.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
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- Definition

The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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-Publisher FASB
-Name Accounting Standards Codification
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The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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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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