Summary of Significant Accounting Policies - Useful Lives of Depreciable Assets (Detail)	12 Months Ended
	Oct. 31, 2017
Computer and other equipment | Minimum
Property, Plant and Equipment [Line Items]
Useful lives of depreciable assets, years	3 years
Computer and other equipment | Maximum
Property, Plant and Equipment [Line Items]
Useful lives of depreciable assets, years	5 years
Buildings
Property, Plant and Equipment [Line Items]
Useful lives of depreciable assets, years	30 years
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Useful lives of depreciable assets, years	5 years
Leasehold improvements (average)
Property, Plant and Equipment [Line Items]
Useful lives of depreciable assets, years	5 years