Stockholders' Equity - Additional Information (Details) $ / shares in Units, $ in Billions	1 Months Ended			12 Months Ended
	Aug. 31, 2025 shares	Jul. 31, 2024 shares	May 31, 2024 shares	Sep. 30, 2025 USD ($) preferredStockSeries shares	Sep. 30, 2024 USD ($) shares	Sep. 30, 2023 USD ($)	Oct. 28, 2025 $ / shares	Apr. 30, 2025 USD ($)	Oct. 31, 2023 USD ($)
Class of Stock [Line Items]
Stock repurchase program, authorized amount | $								$ 30.0	$ 25.0
Stock repurchase plan, remaining authorized funds | $				$ 24.9
Dividends declared and paid | $				$ 4.6	$ 4.2	$ 3.8
Number of series of preferred stock acquired | preferredStockSeries				3
Subsequent Event
Class of Stock [Line Items]
Dividends declared, quarterly, per share amount (in dollars per share) | $ / shares							$ 0.67
Series A convertible participating preferred stock
Class of Stock [Line Items]
Stock issued under equity plans (in shares)	40,080	99,264
Preferred stock, shares authorized (in shares)				4,000,000	4,000,000
Preferred stock, conversion rate				100.0000	100.0000
Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares authorized (in shares)				25,000,000	25,000,000
Series B Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares authorized (in shares)				2,000,000	2,000,000
Preferred stock, conversion rate				0.6690	1.0030
Series C Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares authorized (in shares)				3,000,000	3,000,000
Preferred stock, conversion rate				0.7640	1.7860
Class A common stock
Class of Stock [Line Items]
Common stock, shares authorized (in shares)				2,000,000,000,000.0
Class B-1 common stock
Class of Stock [Line Items]
Common stock, shares authorized (in shares)				499,000,000
Stock tendered during period, shares, stock exchange offer (in shares)			241,000,000
Class B-2 common stock
Class of Stock [Line Items]
Stock issued under equity plans (in shares)			120,000,000
Common stock, shares authorized (in shares)				123,000,000
Common Class B-3
Class of Stock [Line Items]
Common stock, shares authorized (in shares)				61,000,000
Common Class B-4
Class of Stock [Line Items]
Common stock, shares authorized (in shares)				31,000,000
Common Class B-5
Class of Stock [Line Items]
Common stock, shares authorized (in shares)				15,000,000
Class C common stock
Class of Stock [Line Items]
Stock issued under equity plans (in shares)			48,000,000
Common stock, shares authorized (in shares)				1,100,000,000
Class A equivalent preferred stock | Visa Europe
Class of Stock [Line Items]
Preferred stock, conversion rate				100