Schedule of Restricted Stock Award Activity (Detail) - $ / shares	12 Months Ended
Jul. 31, 2018	Jul. 31, 2017	Jul. 31, 2016
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Nonvested, beginning of year, Shares	1,899	5,806	9,713
Vested, Shares	(1,899)	(3,907)	(3,907)
Nonvested, end of year, Shares		1,899	5,806
Nonvested, beginning of year, Weighted Average Grant Date Fair Value	$ 32.36	$ 31.36	$ 31.16
Vested, Weighted Average Grant Date Fair Value	$ 32.36	30.87	30.87
Nonvested, end of year, Weighted Average Grant Date Fair Value		$ 32.36	$ 31.36
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Nonvested, beginning of year, Shares	332,576	325,136	280,353
Granted, Shares	171,340	166,567	181,872
Vested, Shares	(168,714)	(157,315)	(133,758)
Forfeited, Shares	(6,771)	(1,812)	(3,331)
Nonvested, end of year, Shares	328,431	332,576	325,136
Nonvested, beginning of year, Weighted Average Grant Date Fair Value	$ 69.41	$ 53.95	$ 50.55
Granted, Weighted Average Grant Date Fair Value	124.84	84.85	55.37
Vested, Weighted Average Grant Date Fair Value	64.01	53.87	48.73
Forfeited, Weighted Average Grant Date Fair Value	93.46	64.03	54.18
Nonvested, end of year, Weighted Average Grant Date Fair Value	$ 101.97	$ 69.41	$ 53.95

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

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=109197908&loc=d3e5070-113901

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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.

+ References

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-Topic 718
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-Section 50
-Paragraph 2
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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).

+ References

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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.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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The weighted average fair value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units.

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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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-Publisher FASB
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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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