Consolidated Statement of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2022	Mar. 31, 2021
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 49.4	$ 410.3	$ 288.3	$ 1,000.7
Other comprehensive income (loss):
Pension and other postretirement benefit plan adjustments (net of tax (expense) of ($66.5), ($8.5), ($71.9), and ($16.7))	187.4	28.0	204.3	55.6
Currency translation adjustments	(9.8)	(33.3)	(29.3)	35.9
Net change in cash flow hedges (net of tax (expense) benefit of ($0.6), ($2.7), ($3.2), and $1.0)	1.8	6.6	9.3	(3.2)
Other comprehensive income	179.4	1.3	184.3	88.3
Comprehensive income	228.8	411.6	472.6	1,089.0
Comprehensive loss attributable to noncontrolling interests	(4.2)	(4.7)	(6.8)	(7.5)
Comprehensive income attributable to Rockwell Automation, Inc.	$ 233.0	$ 416.3	$ 479.4	$ 1,096.5