CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 10,301	$ 6,699	$ 5,991	[1]
Investment securities, available-for-sale:
Net unrealized gain	94	60	51
Income tax effect	(19)	(24)	(18)
Reclassification adjustment for net (gain) loss realized in net income	(215)	1	(3)
Income tax effect	50	0	1
Defined benefit pension and other postretirement plans:
Net unrealized actuarial gain (loss) and prior service credit	16	183	(106)
Income tax effect	(5)	(54)	36
Reclassification adjustment for net loss realized in net income	5	32	10
Income tax effect	(1)	(12)	(4)
Derivative instruments classified as cash flow hedges:
Net unrealized gain (loss)	90	(22)	(74)
Income tax effect	(24)	15	9
Reclassification adjustment for net loss (gain) realized in net income	32	33	(103)
Income tax effect	(2)	(12)	35
Foreign currency translation adjustments	(352)	1,136	(218)
Other comprehensive income (loss), net of tax	(331)	1,336	(384)
Comprehensive income	$ 9,970	$ 8,035	$ 5,607

[1] The Company did not include Visa Europe’s financial results in the Company’s consolidated statements of operations from the acquisition date, June 21, 2016, through June 30, 2016 as the impact was immaterial. The Company’s consolidated statement of operations for the year ended September 30, 2016 includes Visa Europe’s financial results for the three months ended September 30, 2016.