Business combinations and disposals (Schedule of the Valuation of the Intangible Assets Acquired) (Details) - Ascend Management Innovations LLC $ in Thousands	9 Months Ended
	Jun. 30, 2017 USD ($)
Business Acquisition [Line Items]
Fair value	$ 22,300
Customer relationships
Business Acquisition [Line Items]
Useful life	19 years
Fair value	$ 20,400
Trade Names
Business Acquisition [Line Items]
Useful life	8 years
Fair value	$ 1,700
Technology-Based Intangible Assets
Business Acquisition [Line Items]
Useful life	1 year
Fair value	$ 200