Earnings Per Share - Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Schedule of Earnings Per Share, Basic and Diluted, by Common Class [Line Items]
Income Allocation - Basic	$ 4,179	$ 3,959
Class A common stock
Schedule of Earnings Per Share, Basic and Diluted, by Common Class [Line Items]
Income Allocation - Basic	$ 3,243	$ 3,065
Weighted- Average Shares Outstanding - Basic (in shares)	1,629	1,669
Earnings per Share - Basic (in dollars per share)	$ 1.99	$ 1.84
Income Allocation - Diluted	$ 4,179	$ 3,959
Weighted- Average Shares Outstanding - Diluted (in shares)	2,102	2,159
Earnings per Share - Diluted (in dollars per share)	$ 1.99	$ 1.83
Class B common stock
Schedule of Earnings Per Share, Basic and Diluted, by Common Class [Line Items]
Income Allocation - Basic	$ 784	$ 732
Weighted- Average Shares Outstanding - Basic (in shares)	245	245
Earnings per Share - Basic (in dollars per share)	$ 3.19	$ 2.98
Income Allocation - Diluted	$ 784	$ 731
Weighted- Average Shares Outstanding - Diluted (in shares)	245	245
Earnings per Share - Diluted (in dollars per share)	$ 3.19	$ 2.98
Weighted-average as-converted common stock used in income allocation (in shares)	394	398
Class C common stock
Schedule of Earnings Per Share, Basic and Diluted, by Common Class [Line Items]
Income Allocation - Basic	$ 78	$ 74
Weighted- Average Shares Outstanding - Basic (in shares)	10	10
Earnings per Share - Basic (in dollars per share)	$ 7.96	$ 7.35
Income Allocation - Diluted	$ 78	$ 74
Weighted- Average Shares Outstanding - Diluted (in shares)	10	10
Earnings per Share - Diluted (in dollars per share)	$ 7.95	$ 7.34
Weighted-average as-converted common stock used in income allocation (in shares)	39	40
Participating securities
Schedule of Earnings Per Share, Basic and Diluted, by Common Class [Line Items]
Income Allocation - Basic	$ 74	$ 88
Income Allocation - Diluted	$ 74	$ 88
Series A preferred stock
Schedule of Earnings Per Share, Basic and Diluted, by Common Class [Line Items]
Weighted-average as-converted common stock used in income allocation (in shares)	13	7
Series B preferred stock
Schedule of Earnings Per Share, Basic and Diluted, by Common Class [Line Items]
Weighted-average as-converted common stock used in income allocation (in shares)	7	16
Series C preferred stock
Schedule of Earnings Per Share, Basic and Diluted, by Common Class [Line Items]
Weighted-average as-converted common stock used in income allocation (in shares)	11	22