Retirement Benefits (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Pension Benefits [Member]
Components of net periodic benefit cost (income)
Service cost	$ 22.1	$ 21.3	$ 66.0	$ 64.5
Interest cost	42.5	41.7	127.2	125.6
Expected return on plan assets	(54.8)	(55.7)	(163.9)	(167.6)
Amortization:
Prior service credit	(0.7)	(0.7)	(2.1)	(2.0)
Net actuarial loss	31.2	29.6	93.4	89.2
Net periodic benefit cost (income)	40.3	36.2	120.6	109.7
Other Postretirement Benefits [Member]
Components of net periodic benefit cost (income)
Service cost	0.4	0.4	1.0	1.2
Interest cost	0.8	1.0	2.5	3.1
Amortization:
Prior service credit	(2.8)	(3.7)	(8.5)	(11.1)
Net actuarial loss	0.6	1.2	1.9	3.5
Net periodic benefit cost (income)	$ (1.0)	$ (1.1)	$ (3.1)	$ (3.3)