Liabilities and Restructuring Charges - Additional Information (Details) - USD ($)	3 Months Ended		12 Months Ended
	Jan. 31, 2018	Jan. 31, 2017	Oct. 31, 2017
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ (282,000)	$ 12,105,000
Employee Severance and Benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges			$ 36,600,000
Cash payments	7,900,000
Employee related restructuring liabilities	$ 9,300,000.0		$ 17,500,000.0