Condensed Consolidated Statements 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	$ 64.0	$ 55.3	$ 105.7	$ 74.8
Other comprehensive (loss)/gain, net of tax:
Foreign currency translation adjustment	1.2	(1.6)	(0.1)	12.3
Cash flow hedges	(18.1)	0.0	(18.2)	0.0
Other comprehensive (loss)/gain, net of tax	(16.9)	(1.6)	(18.3)	12.3
Comprehensive income	$ 47.1	$ 53.7	$ 87.4	$ 87.1