Accumulated Other Comprehensive Loss - Reclassifications out of Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other income (expense)	$ 6.5	$ 19.8	$ (83.3)	$ (1.0)
Sales	2,238.7	1,968.7	6,495.1	5,634.1
Cost of sales	(1,323.3)	(1,166.3)	(3,833.6)	(3,418.5)
Selling, general and administrative expenses	(501.4)	(442.0)	(1,472.1)	(1,318.0)
Interest expense	(34.4)	(30.8)	(104.3)	(90.5)
Income before income taxes	471.8	344.2	1,291.1	667.8
Income tax provision (Note 14)	(73.1)	(49.4)	(218.8)	(84.7)
Net income attributable to Rockwell Automation, Inc.	400.2	297.9	1,084.5	593.3
Reclassification out of accumulated other comprehensive loss
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income attributable to Rockwell Automation, Inc.	(3.2)	2.8	69.9	56.0
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	2.6	9.7	118.8	79.9
Income tax provision (Note 14)	(0.5)	(1.7)	(28.7)	(19.3)
Net income attributable to Rockwell Automation, Inc.	2.1	8.0	90.1	60.6
Amortization of prior service cost (credit) | Reclassification out of accumulated other comprehensive loss
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other income (expense)	0.1	(0.2)	0.1	0.2
Amortization of net actuarial loss (gain) | Reclassification out of accumulated other comprehensive loss
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other income (expense)	0.3	10.6	(1.4)	55.5
Settlement and curtailment charges (benefit) | Reclassification out of accumulated other comprehensive loss
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other income (expense)	2.2	(0.7)	120.1	24.2
Net unrealized losses on cash flow hedges, net of tax | Reclassification out of accumulated other comprehensive loss
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes	(7.3)	(7.2)	(27.7)	(6.6)
Income tax provision (Note 14)	2.0	2.0	7.5	2.0
Net income attributable to Rockwell Automation, Inc.	(5.3)	(5.2)	(20.2)	(4.6)
Net unrealized losses on cash flow hedges, net of tax | Forward exchange contracts | Reclassification out of accumulated other comprehensive loss
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Sales	(1.9)	(0.5)	(4.6)	(0.2)
Cost of sales	(6.3)	(7.9)	(25.7)	(9.5)
Selling, general and administrative expenses	0.0	0.3	(0.1)	0.4
Net unrealized losses on cash flow hedges, net of tax | 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	$ 0.9	$ 0.9	$ 2.7	$ 2.7