Income Taxes (Details) - USD ($) $ in Millions			3 Months Ended	6 Months Ended
Jan. 31, 2021	Aug. 31, 2020	Jan. 31, 2021	Jan. 31, 2020	Jan. 31, 2021	Jan. 31, 2020
Income Tax Disclosure [Abstract]
Excess tax benefits on share-based compensation			$ 12.0	$ 23.0	$ 64.0	$ 52.0
Effective tax rate	26.00%	25.00%	8.00%	15.00%	6.00%	2.00%
Effective tax rate, excluding discrete tax benefits			26.00%	24.00%	26.00%	24.00%
Federal statutory income tax rate					21.00%	21.00%
Total amount of unrecognized tax benefits	$ 168.0		$ 168.0		$ 168.0
Favorable net impact to income tax expense due to recognition of tax benefits	101.0		101.0		101.0
Noncurrent income taxes receivable	$ 70.0		$ 70.0		$ 70.0

Effective Income Tax Rate Reconciliation, Excluding Discrete Tax Benefits, Percent

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

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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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Amount of difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying domestic federal statutory income tax rate to pretax income (loss) from continuing operation, attributable to expense for award under share-based payment arrangement. Excludes expense determined to be nondeductible upon grant or after for award under share-based payment arrangement.

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Carrying amount due after one year of the balance sheet date (or one operating cycle, if longer) from tax authorities as of the balance sheet date representing refunds of overpayments or recoveries based on agreed-upon resolutions of disputes.

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Amount of unrecognized tax benefits.

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The total amount of unrecognized tax benefits that, if recognized, would affect the effective tax rate.

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