Summary of Business and Significant Accounting Policies - Schedule of Estimated Useful Lives by Asset Classification (Detail)	12 Months Ended
	Jan. 31, 2018
Land [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life description	Not depreciated
Building [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	30 years
Land and building improvements [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life description	Shorter of remaining life of building or estimated useful life
Equipment and computers [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Furniture and fixtures [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years
Leasehold improvements [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life description	Shorter of remaining life of the lease term or estimated useful life