Shareowners' Equity - Schedule of Reclassifications Out of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other (expense) income	$ 71.3	$ 1.6	$ (5.7)
Sales	9,058.0	7,760.4	6,997.4
Cost of sales	(5,341.0)	(4,658.4)	(4,099.7)
Selling, general and administrative expenses	(2,023.7)	(1,766.7)	(1,680.0)
Interest expense	(135.3)	(123.2)	(94.6)
Income before income taxes	1,608.5	1,073.6	1,526.2
Income tax provision	(330.5)	(154.5)	(181.9)
Net income attributable to Rockwell Automation, Inc.	1,387.4	932.2	1,358.1
Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income attributable to Rockwell Automation, Inc.	64.2	62.6	156.0
Amortization of prior service cost (credit) | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other (expense) income	0.1	(0.2)	(4.0)
Amortization of net actuarial (gain) loss | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other (expense) income	(2.1)	60.1	142.5
Settlement and curtailment charges | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other (expense) income	123.4	38.6	39.8
Pension and other postretirement benefit plan adjustments, net of tax | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes	121.4	98.5	178.3
Income tax provision	(31.0)	(22.9)	(40.1)
Net income attributable to Rockwell Automation, Inc.	90.4	75.6	138.2
Accumulated gain (loss), net, cash flow hedge, parent | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Sales	(6.0)	(0.7)	(1.9)
Cost of sales	(33.4)	(21.8)	25.4
Selling, general and administrative expenses	0.0	0.9	(1.5)
Interest expense	3.5	3.6	2.3
Income before income taxes	(35.9)	(18.0)	24.3
Income tax provision	9.7	5.0	(6.5)
Net income attributable to Rockwell Automation, Inc.	$ (26.2)	$ (13.0)	$ 17.8