Net Periodic Pension and Other Postretirement Plan Cost (Detail) - USD ($) $ in Millions		12 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Pension Benefits | U.S. Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost		$ 0	$ 13	$ 47
Interest cost		36	40	40
Expected return on assets		(70)	(69)	(72)
Prior service credit		0	(1)	(7)
Actuarial loss (gain)		15	7	1
Net benefit cost		(19)	(10)	9
Curtailment gain		0	(8)	0
Settlement loss		15	13	7
Total net periodic benefit cost		(4)	(5)	16
Pension Benefits | Non-U.S. Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	[1]	6	1
Interest cost	[1]	11	3
Expected return on assets	[1]	(16)	(4)
Prior service credit	[1]	0	0
Actuarial loss (gain)	[1]	2	0
Net benefit cost	[1]	3	0
Curtailment gain	[1]	0	0
Settlement loss	[1]	0	0
Total net periodic benefit cost	[1]	3	0
Other Postretirement Benefits | U.S. Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost		0	0	0
Interest cost		1	1	1
Expected return on assets		0	0	0
Prior service credit		(2)	(3)	(3)
Actuarial loss (gain)		(2)	(2)	(2)
Net benefit cost		(3)	(4)	(4)
Curtailment gain		0	0	0
Settlement loss		0	0	0
Total net periodic benefit cost		$ (3)	$ (4)	$ (4)

[1] For fiscal 2016, it represents Visa Europe's UK pension plans' net pension benefit cost recognized from the Closing through September 30, 2016.