Liabilities and Restructuring Charges - Additional Information (Details) - USD ($)	3 Months Ended		6 Months Ended		12 Months Ended
	Apr. 30, 2018	Apr. 30, 2017	Apr. 30, 2018	Apr. 30, 2017	Oct. 31, 2017
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 2,176,000	$ 12,907,000	$ 1,894,000	$ 25,012,000
Employee Severance and Benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges	1,800,000				$ 36,600,000
Cash payments	9,400,000		17,300,000
Employee related restructuring liabilities	900,000		900,000		$ 17,500,000.0
Minimum | Employee Severance and Benefits
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost	8,000,000		8,000,000
Maximum | Employee Severance and Benefits
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost	$ 10,000,000		$ 10,000,000