Property, plant and equipment, net (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Property, Plant and Equipment [Line Items]
Gross	$ 399.7	$ 392.3
Accumulated depreciation /amortization	(191.4)	(171.3)
Net	208.3	221.0
Depreciation and amortization expense	42.9	40.1	$ 35.0
thereof Amortization of Capitalized Software Development Costs	11.2	9.2	$ 8.8
Land
Property, Plant and Equipment [Line Items]
Gross	10.5	11.9
Accumulated depreciation /amortization	0.0	0.0
Net	10.5	11.9
Buildings, building improvements and leashold improvements
Property, Plant and Equipment [Line Items]
Gross	83.6	79.0
Accumulated depreciation /amortization	(21.9)	(19.5)
Net	61.7	59.5
Machinery and technical equipment
Property, Plant and Equipment [Line Items]
Gross	198.1	200.3
Accumulated depreciation /amortization	(125.6)	(118.3)
Net	72.5	82.0
Software and software licences
Property, Plant and Equipment [Line Items]
Gross	85.2	79.3
Accumulated depreciation /amortization	(43.9)	(33.5)
Net	41.3	45.8
Prepayments for property, plant and equipment
Property, Plant and Equipment [Line Items]
Gross	22.3	21.8
Accumulated depreciation /amortization	0.0	0.0
Net	22.3	21.8
Office space leased under operating leases to third parties
Property, Plant and Equipment [Line Items]
Gross	1.0	1.2
Net	$ 0.2	$ 0.3