Schedule of Differences between Income Taxes at Federal Statutory Rate and Actual Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2015
Income Tax Disclosure [Abstract]
Provision at federal statutory rate	$ 194,735	$ 134,160	$ 102,513
State and local income taxes, net of federal benefit	11,021	6,599	5,144
Federal income tax credits and incentives	(3,228)	(4,194)	(2,207)
Domestic production activities deduction	(19,527)	(12,609)	(9,519)
Change in uncertain tax positions	375	611	(5,650)
Other	(1,244)	724	605
Total income tax expense	$ 182,132	$ 125,291	$ 90,886

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

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-Publisher FASB
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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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