Retirement Benefits (Details 6) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
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
Private equity [Member] | U.S. Pension Benefit Plans [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at beginning of year	70.2
Plan assets at end of year	57.1	70.2
Alternative equity [Member] | U.S. Pension Benefit Plans [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at beginning of year	50.7
Plan assets at end of year	56.9	50.7
Insurance contracts [Member] | U.S. Pension Benefit Plans [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at beginning of year	0.9
Plan assets at end of year	0.9	0.9
Insurance contracts [Member] | Non-U.S. Pension Benefit Plans [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at beginning of year	63.8
Plan assets at end of year	79.7	63.8
Real estate [Member] | Non-U.S. Pension Benefit Plans [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at beginning of year	88.1
Plan assets at end of year	94.6	88.1
Other [Member] | Non-U.S. Pension Benefit Plans [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at beginning of year	4.4
Plan assets at end of year	4.8	4.4
Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at beginning of year	197.4	199.3
Realized Gains (Losses)	7.5	11.2
Unrealized Gains (Losses)	(3.9)	2.2
Purchases, Sales, Issuances, and Settlements, Net	6.2	(15.3)
Plan assets at end of year	207.2	197.4
Fair Value, Inputs, Level 3 [Member] | Private equity [Member] | U.S. Pension Benefit Plans [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at beginning of year	70.2	78.8
Realized Gains (Losses)	5.3	7.2
Unrealized Gains (Losses)	(13.3)	(11.0)
Purchases, Sales, Issuances, and Settlements, Net	(5.1)	(4.8)
Plan assets at end of year	57.1	70.2
Fair Value, Inputs, Level 3 [Member] | Alternative equity [Member] | U.S. Pension Benefit Plans [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at beginning of year	50.7	49.9
Realized Gains (Losses)	2.2	4.0
Unrealized Gains (Losses)	(5.6)	1.7
Purchases, Sales, Issuances, and Settlements, Net	9.6	(4.9)
Plan assets at end of year	56.9	50.7
Fair Value, Inputs, Level 3 [Member] | Insurance contracts [Member] | U.S. Pension Benefit Plans [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at beginning of year	0.9	0.9
Plan assets at end of year	0.9	0.9
Fair Value, Inputs, Level 3 [Member] | Insurance contracts [Member] | Non-U.S. Pension Benefit Plans [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at beginning of year	63.8	57.8
Unrealized Gains (Losses)	14.5	11.3
Purchases, Sales, Issuances, and Settlements, Net	1.4	(5.3)
Plan assets at end of year	79.7	63.8
Fair Value, Inputs, Level 3 [Member] | Real estate [Member] | Non-U.S. Pension Benefit Plans [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at beginning of year	8.7	8.6
Unrealized Gains (Losses)	0.5	0.1
Plan assets at end of year	9.2	8.7
Fair Value, Inputs, Level 3 [Member] | Other [Member] | Non-U.S. Pension Benefit Plans [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at beginning of year	3.1	3.3
Unrealized Gains (Losses)	0.0	0.1
Purchases, Sales, Issuances, and Settlements, Net	0.3	(0.3)
Plan assets at end of year	$ 3.4	$ 3.1