Change in Benefit Obligation (Detail) - Pension Benefits - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
U.S. Plans
Change in Benefit Obligation
Benefit obligation—beginning of fiscal year	$ 913	$ 1,072
Service cost	0	0	$ 13
Interest cost	32	36	40
Actuarial loss (gain)	(38)	(58)
Benefit payments	(63)	(137)
Foreign currency exchange rate changes	0	0
Benefit obligation—end of fiscal year	844	913	1,072
Accumulated benefit obligation	844	913
Change in Plan Assets:
Fair value of plan assets—beginning of fiscal year	1,074	1,077
Actual return on plan assets	78	125
Company contribution	1	9
Benefit payments	(63)	(137)
Foreign currency exchange rate changes	0	0
Fair value of plan assets—end of fiscal year	1,090	1,074	1,077
Funded status at end of fiscal year	246	161
Recognized in Consolidated Balance Sheets:
Non-current asset	252	168
Current liability	(1)	(1)
Non-current liability	(5)	(6)
Funded status at end of fiscal year	246	161
Non-U.S. Plans
Change in Benefit Obligation
Benefit obligation—beginning of fiscal year	433	474
Service cost	4	6	1	[1]
Interest cost	12	11	3	[1]
Actuarial loss (gain)	24	(52)
Benefit payments	(9)	(14)
Foreign currency exchange rate changes	(12)	8
Benefit obligation—end of fiscal year	452	433	474
Accumulated benefit obligation	452	433
Change in Plan Assets:
Fair value of plan assets—beginning of fiscal year	433	415
Actual return on plan assets	13	17
Company contribution	11	5
Benefit payments	(9)	(14)
Foreign currency exchange rate changes	(12)	10
Fair value of plan assets—end of fiscal year	436	433	$ 415
Funded status at end of fiscal year	(16)	0
Recognized in Consolidated Balance Sheets:
Non-current asset	0	5
Current liability	(10)	(5)
Non-current liability	(6)	0
Funded status at end of fiscal year	$ (16)	$ 0

[1] For fiscal 2016, the amounts represent the Visa Europe plans’ net pension benefit cost recognized from the Closing through September 30, 2016.