Goodwill and intangibles, net - Finite-lived intangibles (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Sep. 30, 2012
Finite-Lived Intangible Assets, Net [Abstract]
Finite-Lived Intangible Assets, Gross	$ 258.3
Finite-Lived Intangible Assets, Accumulated Amortization	112.1
Finite-Lived Intangible Assets, Net	146.2
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Future Amortization Expense, Remainder of Fiscal Year		14.8
Future Amortization Expense, Year Two		17.4
Future Amortization Expense, Year Three		15.2
Future Amortization Expense, Year Four		15.2
Future Amortization Expense, Year Five	14.8
Finite-Lived Intangible Assets, Amortization Expense, Year Six	7.3
Finite-Lived Intangible Assets, Amortization Expense, after Year Five	61.5
Tradenames / Brands [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Finite-Lived Intangible Assets, Gross	18.8
Finite-Lived Intangible Assets, Accumulated Amortization	12.1
Finite-Lived Intangible Assets, Net	6.7
Technology and Patents [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Finite-Lived Intangible Assets, Gross	75.3
Finite-Lived Intangible Assets, Accumulated Amortization	50.5
Finite-Lived Intangible Assets, Net	24.8
Customer Related and Other Intangible Assets [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Finite-Lived Intangible Assets, Gross	164.2
Finite-Lived Intangible Assets, Accumulated Amortization	49.5
Finite-Lived Intangible Assets, Net	$ 114.7