Stock-Based Compensation - Summary of Activity for RSUs (Detail) - $ / shares	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
RSUs/SARs - beginning of period	647,394
Granted	417,335	260,341
Vested	(533,007)
Forfeited	(134,833)
RSUs/SARs - end of period	1,137,329
RSUs/SARs, Weighted Average Grant Date Fair Value, Beginning of period	$ 74.04
Weighted Average Grant Date Fair Value, Granted	86.18	$ 112.49
Weighted Average Grant Date Fair Value, Vested	69.11
Weighted Average Grant Date Fair Value, Forfeited	89.58
RSUs/SARs, Weighted Average Grant Date Fair Value, end of period	$ 85.50
Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Accrued dividend shares	4,307
Weighted Average Grant Date Fair Value, Accrued dividend shares	$ 79.20
Electro Scientific Industries Inc [Member] \| Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Assumed shares from ESI Merger	736,133
Weighted Average Grant Date Fair Value, Assumed shares from ESI Merger	$ 84.10

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

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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.

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- Definition

Share based compensation arrangement by share based payment award equity instruments other than options assumed in merger.

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Share based compensation arrangement by share based payment award equity instruments other than options assumed in merger weighted average grant date fair value.

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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

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(3)
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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.

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

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- Definition

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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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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