CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2016		Sep. 30, 2015	Sep. 30, 2014
Statement of Comprehensive Income [Abstract]
Net income	$ 5,991	[1]	$ 6,328	$ 5,438
Investment securities, available-for-sale:
Net unrealized gain (loss)	51		(21)	(44)
Income tax effect	(18)		8	17
Reclassification adjustment for net gain realized in net income	(3)		(21)	(1)
Income tax effect	1		8	0
Defined benefit pension and other postretirement plans:
Net unrealized actuarial gain (loss) and prior service credit	(106)		(122)	(27)
Income tax effect	36		45	8
Amortization of actuarial loss (gain) and prior service credit realized in net income	10		(1)	(8)
Income tax effect	(4)		1	3
Derivative instruments classified as cash flow hedges:
Net unrealized (loss) gain	(74)		172	65
Income tax effect	9		(51)	(13)
Reclassification adjustment for net gain realized in net income	(103)		(102)	(46)
Income tax effect	35		26	9
Foreign currency translation adjustments	(218)		1	(1)
Other comprehensive loss, net of tax	(384)		(57)	(38)
Comprehensive income	$ 5,607		$ 6,271	$ 5,400

[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. See Note 2—Acquisition of Visa Europe.