Retirement Benefits (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Pension Benefits [Member]
Components of net periodic benefit cost
Service cost	$ 19.7	$ 23.1
Interest cost	43.6	40.2
Expected return on plan assets	(54.5)	(56.8)
Amortization:
Prior service credit	(0.7)	(0.6)
Net actuarial loss	24.9	36.3
Net periodic benefit cost	33.0	42.2
Other Postretirement Benefits [Member]
Components of net periodic benefit cost
Service cost	0.5	0.6
Interest cost	1.6	1.6
Amortization:
Prior service credit	(2.5)	(2.7)
Net actuarial loss	0.7	1.1
Net periodic benefit cost	$ 0.3	$ 0.6