Liabilities and Restructuring Charges - Additional Information (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Jul. 31, 2018	Jul. 31, 2017	Jul. 31, 2018	Jul. 31, 2017	Oct. 31, 2017
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 23,000	$ 6,026,000	$ 1,917,000	$ 31,038,000
Employee Severance and Benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges			1,900,000		$ 36,600,000
Cash payments			17,300,000
Employee related restructuring liabilities	0		0		$ 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