Accumulated Other Comprehensive Loss - Reclassifications out of Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other income (Note 11)	$ 6.0	$ 9.0
Income before income taxes	213.0	260.0
Income tax provision (Note 15)	(35.0)	(47.0)
Sales	1,881.0	2,052.0
Cost of sales	(1,159.0)	(1,257.0)
Selling, general and administrative expenses	(476.0)	(514.0)
Interest expense	(39.0)	(33.0)
Net income attributable to Rockwell Automation, Inc.	184.0	215.0
Reclassification out of accumulated other comprehensive loss
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income attributable to Rockwell Automation, Inc.	5.0	(6.0)
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	7.0	0.0
Income tax provision (Note 15)	(2.0)	0.0
Net income attributable to Rockwell Automation, Inc.	5.0	0.0
Amortization of net actuarial loss | Reclassification out of accumulated other comprehensive loss
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other income (Note 11)	7.0	0.0
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]
Income before income taxes	0.0	(8.0)
Income tax provision (Note 15)	0.0	2.0
Net income attributable to Rockwell Automation, Inc.	0.0	(6.0)
Net unrealized losses (gains) on cash flow hedges | Forward exchange contracts | Reclassification out of accumulated other comprehensive loss
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Sales	1.0	(1.0)
Cost of sales	(2.0)	(8.0)
Selling, general and administrative expenses	0.0	0.0
Net unrealized losses (gains) on cash flow hedges | Treasury locks related to 2019 and 2021 debt issuances | Reclassification out of accumulated other comprehensive loss
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense	$ 1.0	$ 1.0