Retirement Benefits (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Pension Benefits [Member]
Components of net periodic benefit cost
Service cost	$ 21.3	$ 19.7	$ 64.5	$ 59.0
Interest cost	41.7	43.6	125.6	130.8
Expected return on plan assets	(55.7)	(54.5)	(167.6)	(163.5)
Amortization:
Prior service credit	(0.7)	(0.7)	(2.0)	(2.1)
Net actuarial loss	29.6	25.0	89.2	74.8
Net periodic benefit cost	36.2	33.1	109.7	99.0
Other Postretirement Benefits [Member]
Components of net periodic benefit cost
Service cost	0.4	0.5	1.2	1.5
Interest cost	1.0	1.7	3.1	4.9
Amortization:
Prior service credit	(3.7)	(2.6)	(11.1)	(7.8)
Net actuarial loss	1.2	0.8	3.5	2.4
Net periodic benefit cost	$ (1.1)	$ 0.4	$ (3.3)	$ 1.0