Condensed Consolidated Statement of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Condensed Consolidated Statement of Other Comprehensive Income (Loss) [Abstract]
Net income	$ 39.3	$ 23.4	$ 55.6	$ 41.6
Other comprehensive (loss) income:
Foreign currency translation adjustment	(3.4)	0.0	(2.7)	0.3
Other comprehensive (loss) income	(3.4)	0.0	(2.7)	0.3
Comprehensive income	$ 35.9	$ 23.4	$ 52.9	$ 41.9