Retirement Benefits (Details 5) - USD ($) $ in Millions	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Investments measured at fair value
Defined benefit plan fair value of plan assets	$ 3,447.9	$ 3,262.5
Fair Value, Inputs, Level 1 [Member]
Investments measured at fair value
Defined benefit plan fair value of plan assets	1,225.5	1,062.3
Fair Value, Inputs, Level 2 [Member]
Investments measured at fair value
Defined benefit plan fair value of plan assets	2,015.2	2,002.8
Fair Value, Inputs, Level 3 [Member]
Investments measured at fair value
Defined benefit plan fair value of plan assets	207.2	197.4	$ 199.3
Cash and Cash Equivalents [Member] | U.S. Pension Benefit Plans [Member]
Investments measured at fair value
Defined benefit plan fair value of plan assets	2.9	5.1
Cash and Cash Equivalents [Member] | Non-U.S. Pension Benefit Plans [Member]
Investments measured at fair value
Defined benefit plan fair value of plan assets	1.9	2.3
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member] | U.S. Pension Benefit Plans [Member]
Investments measured at fair value
Defined benefit plan fair value of plan assets	2.9	5.1
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member] | Non-U.S. Pension Benefit Plans [Member]
Investments measured at fair value
Defined benefit plan fair value of plan assets	1.9	2.3
Common stock [Member] | U.S. Pension Benefit Plans [Member]
Investments measured at fair value
Defined benefit plan fair value of plan assets	705.9	628.5
Common stock [Member] | Non-U.S. Pension Benefit Plans [Member]
Investments measured at fair value
Defined benefit plan fair value of plan assets	48.6	37.0
Common stock [Member] | Fair Value, Inputs, Level 1 [Member] | U.S. Pension Benefit Plans [Member]
Investments measured at fair value
Defined benefit plan fair value of plan assets	705.9	628.5
Common stock [Member] | Fair Value, Inputs, Level 1 [Member] | Non-U.S. Pension Benefit Plans [Member]
Investments measured at fair value
Defined benefit plan fair value of plan assets	48.6	37.0
Mutual funds [Member] | U.S. Pension Benefit Plans [Member]
Investments measured at fair value
Defined benefit plan fair value of plan assets	203.6	174.6
Mutual funds [Member] | Fair Value, Inputs, Level 1 [Member] | U.S. Pension Benefit Plans [Member]
Investments measured at fair value
Defined benefit plan fair value of plan assets	203.6	174.6
Equity Common collective trusts [Member] | U.S. Pension Benefit Plans [Member]
Investments measured at fair value
Defined benefit plan fair value of plan assets	483.6	467.5
Equity Common collective trusts [Member] | Non-U.S. Pension Benefit Plans [Member]
Investments measured at fair value
Defined benefit plan fair value of plan assets	279.3	259.5
Equity Common collective trusts [Member] | Fair Value, Inputs, Level 2 [Member] | U.S. Pension Benefit Plans [Member]
Investments measured at fair value
Defined benefit plan fair value of plan assets	483.6	467.5
Equity Common collective trusts [Member] | Fair Value, Inputs, Level 2 [Member] | Non-U.S. Pension Benefit Plans [Member]
Investments measured at fair value
Defined benefit plan fair value of plan assets	279.3	259.5
Corporate debt [Member] | U.S. Pension Benefit Plans [Member]
Investments measured at fair value
Defined benefit plan fair value of plan assets	591.8	643.8
Corporate debt [Member] | Non-U.S. Pension Benefit Plans [Member]
Investments measured at fair value
Defined benefit plan fair value of plan assets	34.1	40.0
Corporate debt [Member] | Fair Value, Inputs, Level 2 [Member] | U.S. Pension Benefit Plans [Member]
Investments measured at fair value
Defined benefit plan fair value of plan assets	591.8	643.8
Corporate debt [Member] | Fair Value, Inputs, Level 2 [Member] | Non-U.S. Pension Benefit Plans [Member]
Investments measured at fair value
Defined benefit plan fair value of plan assets	34.1	40.0
U.S. Government Securities [Member] | U.S. Pension Benefit Plans [Member]
Investments measured at fair value
Defined benefit plan fair value of plan assets	352.1	333.3
U.S. Government Securities [Member] | Fair Value, Inputs, Level 1 [Member] | U.S. Pension Benefit Plans [Member]
Investments measured at fair value
Defined benefit plan fair value of plan assets	252.6	212.0
U.S. Government Securities [Member] | Fair Value, Inputs, Level 2 [Member] | U.S. Pension Benefit Plans [Member]
Investments measured at fair value
Defined benefit plan fair value of plan assets	99.5	121.3
Non-U.S. Government securities [Member] | Non-U.S. Pension Benefit Plans [Member]
Investments measured at fair value
Defined benefit plan fair value of plan assets	17.6	9.4
Non-U.S. Government securities [Member] | Fair Value, Inputs, Level 1 [Member] | Non-U.S. Pension Benefit Plans [Member]
Investments measured at fair value
Defined benefit plan fair value of plan assets	10.0	2.8
Non-U.S. Government securities [Member] | Fair Value, Inputs, Level 2 [Member] | Non-U.S. Pension Benefit Plans [Member]
Investments measured at fair value
Defined benefit plan fair value of plan assets	7.6	6.6
Fixed income securities Common collective trusts [Member] | U.S. Pension Benefit Plans [Member]
Investments measured at fair value
Defined benefit plan fair value of plan assets	161.4	124.8
Fixed income securities Common collective trusts [Member] | Non-U.S. Pension Benefit Plans [Member]
Investments measured at fair value
Defined benefit plan fair value of plan assets	271.1	258.6
Fixed income securities Common collective trusts [Member] | Fair Value, Inputs, Level 2 [Member] | U.S. Pension Benefit Plans [Member]
Investments measured at fair value
Defined benefit plan fair value of plan assets	161.4	124.8
Fixed income securities Common collective trusts [Member] | Fair Value, Inputs, Level 2 [Member] | Non-U.S. Pension Benefit Plans [Member]
Investments measured at fair value
Defined benefit plan fair value of plan assets	271.1	258.6
Private equity [Member] | U.S. Pension Benefit Plans [Member]
Investments measured at fair value
Defined benefit plan fair value of plan assets	57.1	70.2
Private equity [Member] | Fair Value, Inputs, Level 3 [Member] | U.S. Pension Benefit Plans [Member]
Investments measured at fair value
Defined benefit plan fair value of plan assets	57.1	70.2	78.8
Alternative equity [Member] | U.S. Pension Benefit Plans [Member]
Investments measured at fair value
Defined benefit plan fair value of plan assets	56.9	50.7
Alternative equity [Member] | Fair Value, Inputs, Level 3 [Member] | U.S. Pension Benefit Plans [Member]
Investments measured at fair value
Defined benefit plan fair value of plan assets	56.9	50.7	49.9
Insurance contracts [Member] | U.S. Pension Benefit Plans [Member]
Investments measured at fair value
Defined benefit plan fair value of plan assets	0.9	0.9
Insurance contracts [Member] | Non-U.S. Pension Benefit Plans [Member]
Investments measured at fair value
Defined benefit plan fair value of plan assets	79.7	63.8
Insurance contracts [Member] | Fair Value, Inputs, Level 3 [Member] | U.S. Pension Benefit Plans [Member]
Investments measured at fair value
Defined benefit plan fair value of plan assets	0.9	0.9	0.9
Insurance contracts [Member] | Fair Value, Inputs, Level 3 [Member] | Non-U.S. Pension Benefit Plans [Member]
Investments measured at fair value
Defined benefit plan fair value of plan assets	79.7	63.8	57.8
Real estate [Member] | Non-U.S. Pension Benefit Plans [Member]
Investments measured at fair value
Defined benefit plan fair value of plan assets	94.6	88.1
Real estate [Member] | Fair Value, Inputs, Level 2 [Member] | Non-U.S. Pension Benefit Plans [Member]
Investments measured at fair value
Defined benefit plan fair value of plan assets	85.4	79.4
Real estate [Member] | Fair Value, Inputs, Level 3 [Member] | Non-U.S. Pension Benefit Plans [Member]
Investments measured at fair value
Defined benefit plan fair value of plan assets	9.2	8.7	8.6
Other [Member] | Non-U.S. Pension Benefit Plans [Member]
Investments measured at fair value
Defined benefit plan fair value of plan assets	4.8	4.4
Other [Member] | Fair Value, Inputs, Level 2 [Member] | Non-U.S. Pension Benefit Plans [Member]
Investments measured at fair value
Defined benefit plan fair value of plan assets	1.4	1.3
Other [Member] | Fair Value, Inputs, Level 3 [Member] | Non-U.S. Pension Benefit Plans [Member]
Investments measured at fair value
Defined benefit plan fair value of plan assets	$ 3.4	$ 3.1	$ 3.3