Accumulated Other Comprehensive Loss - Schedule of Reclassifications out of Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other income	$ 22	$ 5	$ 39	$ 8
Sales	2,313	2,144	6,657	6,026
Cost of sales	(1,169)	(1,098)	(3,372)	(3,130)
Interest expense	(33)	(41)	(101)	(119)
Income before income taxes	470	342	1,252	854
Income tax provision	(62)	(49)	(191)	(135)
Net income attributable to Rockwell Automation, Inc.	408	295	1,063	731
Reclassification out of accumulated other comprehensive loss
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income attributable to Rockwell Automation, Inc.	4	7	14	13
Pension and other postretirement benefit plan adjustments | Reclassification out of accumulated other comprehensive loss
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes	4	7	13	22
Income tax provision	(1)	(1)	(3)	(5)
Net income attributable to Rockwell Automation, Inc.	3	6	10	17
Amortization of net actuarial loss | Reclassification out of accumulated other comprehensive loss
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other income	4	7	13	22
Net unrealized losses (gains) on cash flow hedges | Reclassification out of accumulated other comprehensive loss
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Sales	(1)	0	(1)	2
Cost of sales	1	0	4	(11)
Interest expense	2	1	3	3
Income before income taxes	2	1	6	(6)
Income tax provision	(1)	0	(2)	2
Net income attributable to Rockwell Automation, Inc.	$ 1	$ 1	$ 4	$ (4)