Employee Benefit Obligations - Components of Consolidated Net Periodic Benefit and Deferred Compensation Benefit Costs and Contributions Made (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	$ 204.5	$ 190.8
Pension Plan, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	204.5	190.8	168.6
Components of net periodic benefit cost:
Service cost	3.5	3.0
Interest cost	11.2	10.6
Recognized net actuarial loss	(15.3)	(1.1)
Employee contributions	0	(0.1)
Contributions made during period	13.8	12.9
Pension Plan, Defined Benefit | US Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	78.0	73.8
Pension Plan, Defined Benefit | International Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	$ 126.5	$ 117.0