Subsequent events (Details) $ in Millions	12 Months Ended
	Oct. 31, 2016 USD ($) Rate
Subsequent Event [Line Items]
Restructuring and Related Cost, Number of Positions Eliminated, Inception to Date Percent | Rate	17.00%
Restructuring and Related Cost, Expected Number of Positions Eliminated	96
Restructuring and Related Cost, Expected Cost | $	$ 3.0