Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jan. 31, 2020	Jan. 31, 2019	Jan. 31, 2020	Jan. 31, 2019	Jul. 31, 2019
Income Tax Disclosure [Abstract]
Tax benefit, share based compensation	$ 23	$ 8	$ 52	$ 49
Income tax provision (benefit)	(42)	(46)	(7)	2
Income (loss) before income taxes	$ 282	$ 235	$ 304	$ 221
Effective tax rate	15.00%	20.00%	2.00%
Effective tax rate, excluding discrete tax benefits			24.00%	23.00%
Federal statutory income tax rate			21.00%
Total amount of unrecognized tax benefits					$ 120
Unrecognized tax benefits, net of related deferred tax assets					75
Favorable net impact to income tax expense due to recognition of tax benefits					$ 75
Changes in unrecognized tax benefits			$ 0
Long-term income tax receivable	$ 52		$ 52

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

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Unrecognized Tax Benefits, Net of Related Deferred Tax Assets

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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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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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Amount of income (loss) from continuing operations before deduction of income tax expense (benefit) and income (loss) attributable to noncontrolling interest, and addition of income (loss) from equity method investments.

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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 increase (decrease) in unrecognized tax benefits attributable to uncertain tax positions taken in tax returns.

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