Income Taxes - Components of Net Deferred Tax Asset and Liability Accounts (Details) - USD ($) $ in Millions	Sep. 30, 2019	Sep. 30, 2018
Deferred tax assets:
Interest rate swaps	$ 4.9	$ 4.5
Self-insurance reserves	23.7	22.4
Deferred compensation	2.8	2.9
Deferred rent	0.4	0.2
Payroll related accruals	11.2	9.9
Other accrued expenses	2.3	2.5
Allowance for doubtful accounts	1.3	1.5
Net operating loss carryforward	5.0	4.5
Other non-current deferred tax assets	0.9	0.2
Total non-current deferred tax assets	52.5	48.6
Total deferred tax assets	52.5	48.6
Deferred tax liabilities:
Intangible assets	60.9	68.5
Property and equipment	42.8	35.7
Inventories	4.7	4.1
Deferred revenue	7.8	6.8
Prepaid assets	0.3	0.1
Other non-current deferred tax liabilities	0.4	0.6
Total non-current deferred tax liabilities	116.9	115.8
Total deferred tax liabilities	$ 64.4	$ 67.2