Consolidated Statement of Comprehensive Income - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 590.4	$ 315.4
Other comprehensive income (loss), net of tax:
Pension and other postretirement benefit plan adjustments (net of tax (expense) of ($8.2) and ($7.9))	27.6	27.4
Currency translation adjustments	69.2	22.1
Net change in unrealized gains and losses on cash flow hedges (net of tax benefit of $3.7 and $1.1)	(9.8)	(2.5)
Other comprehensive income	87.0	47.0
Comprehensive income	677.4	362.4
Comprehensive (loss) income attributable to noncontrolling interests	(2.8)	5.0
Comprehensive income attributable to Rockwell Automation, Inc.	$ 680.2	$ 357.4