Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Sep. 30, 2016	Sep. 30, 2015
Gross Deferred Tax Assets
Tax loss carryforwards	$ 13.2	$ 57.3
Tax credit carryforwards	64.2	49.6
Retirement benefits and compensation accruals	7.6	7.8
Reserves and accruals	8.4	7.7
Other	3.3	1.8
Valuation allowance	(55.6)	(77.7)
Deferred Tax Assets	41.1	46.5
Gross Deferred Tax Liabilities
Intangible assets	41.0	41.9
Plant and equipment	22.2	24.5
Unremitted earnings of foreign entities	2.3	4.3
Partnership investments	1.3	1.4
Other	6.3	6.7
Deferred Tax Liabilities	73.1	78.8
Net Deferred Income Tax Liability	$ 32.0	$ 32.1