Schedule of Differences between Income Taxes at Federal Statutory Rate and Actual Income Taxes (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Jul. 31, 2014	Jul. 31, 2013	Jul. 31, 2012
Reconciliation of Statutory Federal Tax Rate [Line Items]
Provision at federal statutory rate	$ 88,487	$ 77,691	$ 57,886
State and local income taxes, net of federal benefit	3,748	2,815	846
Federal income tax credits and incentives	(772)	(2,468)	(831)
Domestic production activities deduction	(7,947)	(7,303)	(5,145)
Change in uncertain tax positions	(6,631)	(718)	1,879
Executive compensation limitation			38
Change in current tax payable and deferred tax liabilities	125	13	(1,018)
Other permanent items	293	266	298
Total income tax expense	$ 77,303	$ 70,296	$ 53,953

Income Tax Reconciliation Other Permanent Items

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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.4-08.(h))

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-Name Regulation S-X (SX)

-Number 210

-Section 08

-Paragraph h

-Article 4

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-Publisher FASB

-Name Accounting Standards Codification

-Glossary Income Tax Expense (or Benefit)

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 50

-Paragraph 9

-Subparagraph (a),(b)

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Amount of the difference between reported income tax expense (benefit) and the expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to deduction for qualified production activity.

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The amount of income tax expense or benefit for the period computed by applying the domestic federal statutory tax rates to pretax income from continuing operations.

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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to increase (decrease) in income tax contingencies. Including, but not limited to, domestic tax contingency, foreign tax contingency, state and local tax contingency, and other contingencies.

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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to tax credits. Including, but not limited to, research credit, foreign tax credit, investment tax credit, and other tax credits.

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