Summary of Significant Accounting Policies - Adoption of 606 (Details) - USD ($) $ in Millions	Jun. 30, 2019	Oct. 01, 2018	Sep. 30, 2018
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Current portion of client incentives	$ 690	$ 539	$ 340
Client incentives	1,854	1,152	538
Client incentives	3,690	3,075	2,834
Accrued liabilities	1,358	1,166	1,160
Deferred tax liabilities	4,930	4,726	4,618
Other liabilities	2,801	2,724	2,666
Accumulated income	13,040	11,718	$ 11,318
Impact of the New Revenue Standard \| Accounting Standards Update 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Current portion of client incentives	(282)	199
Client incentives	(811)	614
Client incentives	(439)	241
Accrued liabilities	(18)	6
Deferred tax liabilities	(112)	108
Other liabilities	(110)	58
Accumulated income	$ (440)	$ 400

Carrying value as of the balance sheet date of obligations incurred and payable, pertaining to costs that are statutory in nature, are incurred on contractual obligations, or accumulate over time and for which invoices have not yet been received or will not be rendered. Examples include taxes, interest, rent and utilities. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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The Company enters into incentive agreements with financial institution customers, merchants, and other business partners designed to build payments volume and to increase product acceptance. The Company capitalizes certain incentive payments under these agreements related to signing or renewing long-term contracts in instances where the Company receives a performance commitment, from the customer, to generate a substantial portion of its credit or debit card payments volume on Visa branded products for an agreed upon period of time. Incentives are accrued based on management's estimate of the customers' performance according to the provisions in the related agreements. These accruals are regularly reviewed and estimates of performance are adjusted as appropriate. Capitalized amounts are amortized and the Company's estimated obligations under these agreements are primarily charged as a reduction of operating revenue over the period of benefit.

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