Stockholders' Equity - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2022	Mar. 31, 2021	Apr. 22, 2022	Dec. 31, 2021	Jan. 31, 2021
Stockholders Equity Note [Line Items]
Share repurchase program						$ 12,000	$ 8,000
Share repurchase programs authorized	$ 9,800		$ 9,800
Cash dividends declared and paid, at a quarterly amount per Class A share	$ 802	$ 701	$ 1,611	$ 1,404
Subsequent Event | Class A common stock
Stockholders Equity Note [Line Items]
Quarterly cash dividend (in dollars per share)					$ 0.375