Retirement Benefits (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2016	Mar. 31, 2015	Sep. 30, 2015
Defined Benefit Plan Disclosure [Line Items]
Company contributions			$ 60.2	$ 95.4	$ 137.5
Pension settlement loss	$ 2.6	$ 12.6	2.6	$ 12.6
Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Total expected contributions for current fiscal year			100.0
Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Total expected contributions for current fiscal year			120.0
Change in Assumptions for Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Estimated impact of change in accounting estimate on net periodic benefit cost in the current fiscal year			$ (30.0)