Retirement Benefits (Change in PBO) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
US [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Obligation at beginning of year	$ 3,002.9	$ 2,809.0
Service cost	42.2	42.6	$ 51.8
Interest cost	124.7	130.7	117.1
Amendments	1.2	1.0
Actuarial (gain) loss	130.4	135.4
Curtailments	5.3	0.0
Settlement (gain) loss	6.7	5.9
Special termination benefits	7.2	0.2
Participant contributions	0.0	0.0
Benefits paid	(181.8)	(123.1)
Other	1.1	1.2
Obligation at End of Year	3,139.9	3,002.9	2,809.0
International [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Obligation at beginning of year	1,735.7	1,585.0
Service cost	31.3	36.0	31.5
Interest cost	57.8	67.2	57.3
Amendments	(3.1)	(0.1)
Actuarial (gain) loss	30.0	130.3
Curtailments	(5.1)	0.0
Settlement (gain) loss	(8.6)	(1.9)
Special termination benefits	1.5	0.1
Participant contributions	2.1	2.4
Benefits paid	(50.3)	(50.1)
Currency translation/other	(143.4)	(33.2)
Obligation at End of Year	1,647.9	1,735.7	1,585.0
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Obligation at beginning of year	93.5	99.9
Service cost	2.8	3.3	4.3
Interest cost	2.2	2.3	1.9
Actuarial (gain) loss	(2.3)	(3.0)
Benefits paid	(9.3)	(9.0)
Obligation at End of Year	$ 86.9	$ 93.5	$ 99.9