Income Taxes (Significant Components of Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Millions	Sep. 30, 2015	Sep. 30, 2014
Deferred Tax Assets, Gross [Abstract]
Retirement benefits and compensation accruals	$ 468.7	$ 348.9
Tax loss carryforwards	116.7	125.0
Tax credits and other tax carryforwards	43.8	78.1
Reserves and accruals	71.9	80.1
Other	57.3	46.1
Valuation allowance	(103.6)	(103.8)
Deferred Tax Assets	654.8	574.4
Deferred Tax Liabilities, Gross [Abstract]
Plant and equipment	1,124.6	1,089.5
Currency gains	65.7	18.2
Unremitted earnings of foreign entities	34.3	100.0
Intangible assets	135.6	150.0
Other	15.3	22.8
Deferred Tax Liabilities	1,375.5	1,380.5
Net Deferred Income Tax Liabilities	$ 720.7	$ 806.1