Stockholders' Equity - Additional Information (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	1 Months Ended	3 Months Ended		6 Months Ended
	May 31, 2024	Mar. 31, 2025	Mar. 31, 2024	Mar. 31, 2025	Mar. 31, 2024	Apr. 30, 2025	Apr. 29, 2025	Oct. 31, 2023
Equity, Class of Treasury Stock [Line Items]
Share repurchase program								$ 25,000
Share repurchase programs authorized		$ 4,700		$ 4,700
Dividends paid		$ 1,164	$ 1,060	$ 2,300	$ 2,100
Class B-1 common stock
Equity, Class of Treasury Stock [Line Items]
Stock tendered during period, shares, stock exchange offer (in shares)	241
Class B-2 common stock
Equity, Class of Treasury Stock [Line Items]
Stock issued during the period, new issues (in shares)	120
Class C common stock
Equity, Class of Treasury Stock [Line Items]
Stock issued during the period, new issues (in shares)	48
Subsequent Event
Equity, Class of Treasury Stock [Line Items]
Share repurchase program						$ 30,000
Quarterly cash dividend (in dollars per share)							$ 0.59