Revenue Recognition - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Sep. 30, 2021
Disaggregation of Revenue [Line Items]
Hardware revenue	$ 7.3	$ 6.6
Current contract acquisition costs	49.4		$ 40.5
Noncurrent contract acquisition costs	91.9		86.1
Amortization expense related to contract acquisition costs	7.0	$ 4.7
Short-term contract costs	22.8		21.3
Long-term costs	35.5		35.3
Noncurrent contract assets	73.9		88.9
Current contract assets	65.2		$ 72.6
Deferred revenue	$ 360.5
Minimum
Disaggregation of Revenue [Line Items]
Hosting contract term	1 year
Contract acquisition term	1 year
Maximum
Disaggregation of Revenue [Line Items]
Hosting contract term	5 years
Contract acquisition term	5 years