Property and Equipment - Additional Information (Detail) ft² in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2017 USD ($)	Jul. 31, 2016 USD ($)	Jul. 31, 2017 USD ($)	Jul. 31, 2016 USD ($)	Jan. 31, 2017 USD ($)	Dec. 31, 2013 ft²
Property, Plant and Equipment [Line Items]
Depreciation and amortization expense	$ 94,900	$ 80,100	$ 183,000	$ 155,700
Fixed assets acquired under capital lease agreements	729,600		729,600		$ 729,000
Net rentable area (in square feet) | ft²						445
Property and equipment, gross	3,230,195		3,230,195		2,985,884
Financing obligation - leased facility, current	19,797		19,797		19,594
Financing obligation - leased facility	199,539		199,539		200,711
Expected financing obligation	311,695		311,695
Computers, equipment and software
Property, Plant and Equipment [Line Items]
Accumulated depreciation and amortization	430,400		430,400		386,900
Property and equipment, gross	1,555,572		1,555,572		1,440,986
Buildings and building improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	623,411		623,411		621,377
Construction costs capitalized
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 178,800		$ 178,800		$ 178,800