Schedule of Restructuring Charges (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended	9 Months Ended
	Apr. 30, 2016	Jan. 31, 2016	Oct. 31, 2015	Apr. 30, 2015	Jan. 31, 2016	Apr. 30, 2016	Apr. 30, 2015
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 4.1			$ 5.2		$ 12.6	$ 5.8
2016 First Quarter Actions
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0.0			0.0		12.6	0.0
2015 Actions
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0.0			5.2		2.3	5.8
Cost of sales
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0.8			2.5		4.9	3.2
Operating expenses
Restructuring Cost and Reserve [Line Items]
Restructuring charges	3.3			2.7		7.7	2.6
One-time Termination Benefits | 2016 First Quarter Actions
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 4.1	$ 0.4	$ 5.8	$ 0.0	$ 6.2	$ 4.1	$ 0.0