Retirement Benefits (Schedule of Net Periodic Benefit Cost) (Details) - USD ($) $ in Millions	3 Months Ended																12 Months Ended
	Sep. 30, 2015	[1]	Jun. 30, 2015	[1]	Mar. 31, 2015	[1]	Dec. 31, 2014	[1]	Sep. 30, 2014	[1]	Jun. 30, 2014	[1]	Mar. 31, 2014	[1]	Dec. 31, 2013	[1]	Sep. 30, 2015		Sep. 30, 2014		Sep. 30, 2013
Defined Benefit Plan Disclosure [Line Items]
Settlement loss	$ 7.0		$ 1.6		$ 12.6		$ 0.0		$ 5.5		$ 0.0		$ 0.0		$ 0.0		$ 21.2	[1]	$ 5.5	[1]	$ 12.4
US [Member]
Retirement Benefits [Abstract]
Defined Benefit Plan Recognized Gain Loss Due to Curtailments																	(5.3)		0.0		0.0
Defined Benefit Plan Disclosure [Line Items]
Service cost																	42.2		42.6		51.8
Interest cost																	124.7		130.7		117.1
Expected return on plan assets																	(202.0)		(187.8)		(185.4)
Actuarial loss amortization																	78.9		78.3		116.0
Prior service cost amortization																	2.8		2.9		2.9
Settlement loss																	18.9		4.8		11.5
Curtailments																	5.3		0.0		0.0
Special termination benefits																	7.2		0.2		1.2
Other																	1.0		0.0		0.0
Net periodic benefit cost																	79.0		71.7		115.1
International [Member]
Retirement Benefits [Abstract]
Defined Benefit Plan Recognized Gain Loss Due to Curtailments																	0.0		0.0		0.0
Defined Benefit Plan Disclosure [Line Items]
Service cost																	31.3		36.0		31.5
Interest cost																	57.8		67.2		57.3
Expected return on plan assets																	(79.8)		(78.1)		(71.2)
Actuarial loss amortization																	41.4		36.1		27.0
Prior service cost amortization																	0.0		0.2		0.2
Settlement loss																	2.3		0.7		0.9
Curtailments																	0.0		0.0		0.0
Special termination benefits																	1.5		0.1		6.2
Other																	2.1		2.0		2.7
Net periodic benefit cost																	56.6		64.2		54.6
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost																	2.8		3.3		4.3
Interest cost																	2.2		2.3		1.9
Actuarial loss amortization																	0.8		1.7		2.3
Net periodic benefit cost																	$ 5.8		$ 7.3		$ 8.5

[1] For additional information, see Note 16, Retirement Benefits.