Fair Value Measurements and Investments - Additional Information (Detail) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
	Feb. 01, 2022	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2022	Mar. 31, 2021	Sep. 30, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities due within one year		$ 1,500		$ 1,500
Debt securities due within one to five years		2,300		2,300
Unrealized gains (losses) on equity securities held as of the end of the period		(156)	$ 147	16	$ 176
Impairment of indefinite-lived intangible assets and goodwill	$ 0
Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying value of debt		20,700		20,700		$ 21,000
Estimated Fair Value | Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated fair value of debt		$ 20,800		$ 20,800		$ 22,500