Restructuring Charges (Details) - USD ($)	3 Months Ended				6 Months Ended	9 Months Ended		15 Months Ended
	Apr. 30, 2016	Jan. 31, 2016	Oct. 31, 2015	Apr. 30, 2015	Jan. 31, 2016	Apr. 30, 2016	Apr. 30, 2015	Jan. 31, 2016	Jan. 31, 2015
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 4,100,000			$ 5,200,000		$ 12,600,000	$ 5,800,000
2016 First Quarter Actions
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0			0		12,600,000	0
2016 First Quarter Actions | Engine Product segment
Restructuring Cost and Reserve [Line Items]
Restructuring reserve			$ 0
2015 Actions
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0			5,200,000		2,300,000	5,800,000
2015 Actions | Engine Product segment
Restructuring Cost and Reserve [Line Items]
Expected restructuring costs									$ 5,800,000
Restructuring charges								$ 5,800,000
One-time Termination Benefits | 2016 First Quarter Actions
Restructuring Cost and Reserve [Line Items]
Expected restructuring costs	5,500,000		7,200,000			5,500,000
Restructuring charges	4,100,000	$ 400,000	$ 5,800,000	$ 0	$ 6,200,000	4,100,000	$ 0
One-time Termination Benefits | 2016 First Quarter Actions | Engine Product segment
Restructuring Cost and Reserve [Line Items]
Restructuring charges	1,100,000					7,200,000
One-time Termination Benefits | 2016 First Quarter Actions | Industrial Product segment
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 3,000,000					$ 5,400,000