Income Taxes (Details 2) - USD ($) $ in Millions	Sep. 30, 2017	Sep. 30, 2016
Deferred income tax assets:
Compensation and benefits	$ 18.8	$ 16.2
Inventory	20.2	18.0
Returns, rebates and incentives	45.9	55.1
Retirement benefits	305.5	493.6
Environmental remediation and other site-related costs	33.4	34.8
Share-based compensation	32.4	40.6
Other accruals and reserves	71.3	60.5
Net operating loss carryforwards	20.4	24.4
Tax credit carryforwards	15.3	13.7
Capital loss carryforwards	10.3	9.9
Other	11.1	11.4
Subtotal	584.6	778.2
Valuation allowance	(18.6)	(17.3)
Net deferred income tax assets	566.0	760.9
Deferred income tax liabilities:
Property	(74.0)	(63.5)
Intangible assets	(45.9)	(54.9)
Other	(2.5)	(8.6)
Deferred income tax liabilities	(122.4)	(127.0)
Total net deferred income tax assets	$ 443.6	$ 633.9