Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Statement of Comprehensive Income [Abstract]
Net income	$ 34.2	$ 36.6	$ 109.0	$ 92.2
Other comprehensive income/(loss):
Foreign currency translation adjustment	4.0	0.0	16.3	(2.7)
Other comprehensive income/(loss)	4.0	0.0	16.3	(2.7)
Comprehensive income	$ 38.2	$ 36.6	$ 125.3	$ 89.5