Retirement Benefits (Narrative) (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2010
Defined Benefit Plan Disclosure [Line Items]
Total expected contributions for next fiscal year	$ 275.0
Recognized settlement charges	0	0	(11.5)
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
ABO for all defined benefit pension plans	4,012.6	3,379.5
Pension arrangements not funded because of jurisdictional practice, accumulated benefit obligation	166.5
Pension arrangements not funded because of jurisdictional practice, projected benefit obligation	190.5
Shares of Common Stock in ESOP	4,715,741
Defined Contribution Plan, Cost Recognized	33.9	31.3	30.8
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.70%	2.80%	4.20%
Accumulated postretirement benefit obligation discount rate	1.90%	3.70%
Net actuarial loss	36.5	29.2
Actuarial loss estimated	$ (4.2)