Details of Impairment, Restructuring and Other Charges and Rolls Forward (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2010
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	$ 1.8	$ 27.4	$ 0
Property, plant and equipment impairments	2.1	9.1
Goodwill and intangible asset impairments	3.2	19.4	18.5
Total impairment, restructuring and other charges	$ 7.1	$ 55.9	$ 18.5