Fair Value Measurements and Investments - Additional Information (Detail) - USD ($) $ in Millions		3 Months Ended
		Dec. 31, 2015	Sep. 30, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Visa Europe put option	[1]	$ 0	$ 255
Non-marketable equity investments		47	45
Carrying value of cost method investments, reclassified as available for sale		4
Fair value of available for sale securities previously classified as cost method investments		55
Pre-tax unrealized gain on available-for-sale securities, previously classified as cost method investments		51
Principal Amount		16,000
Long-term Debt		15,877	0
Long-term Debt, Fair Value		16,072
Available-for-sale securities, gross unrealized gains		55	7
Available-for-sale securities, gross unrealized losses		$ 14	$ 0
Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investment securities, stated maturities		1 year
Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investment securities, stated maturities		2 years
Senior Notes | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt maturity period		2 years
Senior Notes | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt maturity period		30 years
Senior Notes | 2017 Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Principal Amount		$ 1,750
Long-term Debt		1,745
Long-term Debt, Fair Value		1,748
Senior Notes | 2020 Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Principal Amount		3,000
Long-term Debt		2,986
Long-term Debt, Fair Value		2,995
Senior Notes | 2022 Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Principal Amount		2,250
Long-term Debt		2,237
Long-term Debt, Fair Value		2,259
Senior Notes | 2025 Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Principal Amount		4,000
Long-term Debt		3,962
Long-term Debt, Fair Value		4,005
Senior Notes | 2035 Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Principal Amount		1,500
Long-term Debt		1,485
Long-term Debt, Fair Value		1,514
Senior Notes | 2045 Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Principal Amount		3,500
Long-term Debt		3,462
Long-term Debt, Fair Value		$ 3,551

[1] On November 2, 2015, the Company and Visa Europe entered into the Put Option Amendment to align certain terms of the Put with the terms of the Visa Europe Transaction Agreement. Exercise of the Amended Put Option by the Visa Europe board of directors is mandatory, subject to the satisfaction of the terms and conditions of the Transaction Agreement. As such, for accounting purposes, it is not treated as a written put option and is not required to be recorded at fair value. At December 31, 2015, Visa expected to complete the transaction in accordance with the Transaction Agreement. Therefore, management concluded that it does not expect the Put to revert to its original, unamended form or to be unilaterally exercised by Visa Europe in the future. As a result, the value of the Put was reduced to zero at December 31, 2015. See Note 2—Visa Europe and Note 4—Fair Value Measurements and Investments.