Condensed Consolidated Statement of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Condensed Consolidated Statement of Other Comprehensive Income (Loss) [Abstract]
Net income	$ 36.6	$ 16.3	$ 92.2	$ 57.9
Other comprehensive (loss) income:
Foreign currency translation adjustment	0.0	0.3	(2.7)	0.6
Other comprehensive (loss) income	0.0	0.3	(2.7)	0.6
Comprehensive income	$ 36.6	$ 16.6	$ 89.5	$ 58.5