Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Income Tax Disclosure [Abstract]
Effective income tax rate reconciliation, percent	41.00%	19.00%	26.00%	19.00%
Adjustment related to the remeasurement of UK deferred tax liabilities	$ 1,000
Recognized tax benefit	51
Recognized tax benefit			$ 147
Increase in unrecognized tax benefits, gross	80
Increase (decrease) in unrecognized tax benefits, net	39		(137)
Decrease in unrecognized tax benefits, gross			37
Increase in accrued interest related to uncertain tax positions	$ 0	$ 18	$ 0	$ 56

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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 12
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Amount of income tax expense (benefit) from continuing operations attributable to an adjustment of a deferred tax liability or asset for enacted changes in tax laws or rates or a change in the tax status of the entity.

+ References

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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 income tax settlements. Including, but not limited to, domestic tax settlement, foreign tax settlement, state and local tax settlement, and other tax settlements.

+ References

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Amount of increase (decrease) to previously recorded tax expense. Includes, but is not limited to, significant settlements of income tax disputes, and unusual tax positions or infrequent actions taken by the entity, including tax assessment reversal, and IRS tax settlement.

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Amount of decrease in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

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Amount of increase in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

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Amount of interest expense for an underpayment of income taxes.

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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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