Stockholders' Equity - Share Repurchases in the Open Market (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Class of Stock [Line Items]
Total cost	$ 11,589	$ 8,676	$ 8,114
Class A common stock
Class of Stock [Line Items]
Shares repurchased in the open market (in shares)	56	40	44
Average repurchase price per share (in dollars per share)	$ 206.47	$ 219.03	$ 183.00
Total cost	$ 11,589	$ 8,676	$ 8,114

Equity impact of the value of stock that has been repurchased and retired during the period. The excess of the purchase price over par value can be charged against retained earnings (once the excess is fully allocated to additional paid in capital).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration