Retirement Benefits (Details 1) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at beginning of year	$ 3,262.5
Plan assets at end of year	3,447.9	$ 3,262.5
Net amount on balance sheet consists of:
Retirement benefits	(1,430.2)	(1,116.6)
Pension Benefits [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation at beginning of year	4,282.2	4,236.6
Service cost	88.0	85.7	$ 78.5
Interest cost	169.5	167.2	174.2
Actuarial losses (gains)	515.4	230.2
Plan amendments	(10.0)	(3.5)
Plan participant contributions	4.3	4.9
Benefits paid	(232.0)	(329.1)
Special termination benefit	0.5	0.0	0.0
Currency translation and other	(32.0)	(109.8)
Benefit obligation at end of year	4,785.9	4,282.2	4,236.6
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at beginning of year	3,262.5	3,591.0
Actual return on plan assets	394.3	29.5
Company contributions	44.3	41.0
Plan participant contributions	4.3	4.9
Benefits paid	(232.0)	(329.1)
Currency translation and other	(25.5)	(74.8)
Plan assets at end of year	3,447.9	3,262.5	3,591.0
Funded status of plans	(1,338.0)	(1,019.7)
Net amount on balance sheet consists of:
Other assets	0.1	0.1
Compensation and benefits	(11.6)	(11.3)
Retirement benefits	(1,326.5)	(1,008.5)
Net amount on balance sheet	(1,338.0)	(1,019.7)
Other Postretirement Benefits [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation at beginning of year	93.3	122.2
Service cost	1.3	1.5	2.0
Interest cost	3.3	4.1	6.5
Actuarial losses (gains)	(0.2)	(20.1)
Plan participant contributions	4.0	5.4
Benefits paid	(14.9)	(17.7)
Special termination benefit	0.0	0.0	0.0
Currency translation and other	0.1	(2.1)
Benefit obligation at end of year	86.9	93.3	122.2
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at beginning of year	0.0	0.0
Actual return on plan assets	0.0	0.0
Company contributions	10.9	12.3
Plan participant contributions	4.0	5.4
Benefits paid	(14.9)	(17.7)
Currency translation and other	0.0	0.0
Plan assets at end of year	0.0	0.0	$ 0.0
Funded status of plans	(86.9)	(93.3)
Net amount on balance sheet consists of:
Other assets	0.0	0.0
Compensation and benefits	(10.5)	(11.4)
Retirement benefits	(76.4)	(81.9)
Net amount on balance sheet	$ (86.9)	$ (93.3)