Income Taxes - Income Taxes Additional Information (Detail) - USD ($)	3 Months Ended	12 Months Ended
	Jul. 31, 2015	Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2014	Jan. 31, 2013
Income Taxes [Line Items]
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount		$ 345,000,000	$ 2,900,000	$ 2,100,000
Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Employee Benefits		233,800,000
Income (Loss) from Continuing Operations before Income Taxes, Foreign		218,200,000	302,500,000	380,500,000
Valuation Allowance, Deferred Tax Asset, Change in Amount		327,200,000	3,600,000	15,900,000
Deferred Tax Liability Not Recognized, Cumulative Amount of Temporary Difference		1,942,200,000
Deferred Tax Liability Not Recognized, Amount of Unrecognized Deferred Tax Liability		544,300,000
Deferred income taxes, net		9,200,000	100,000,000
Net deferred tax assets			185,100,000
Foreign Income Tax Expense (Benefit), Continuing Operations		0	$ 1,200,000	$ 9,700,000
Income Tax Holiday, Income Tax Benefits Per Share			$ 0.01	$ 0.04
Current Foreign Tax Expense (Benefit)		68,400,000	$ 69,500,000	$ 63,900,000
Gross unrecognized tax benefits		254,300,000	245,800,000	222,100,000	$ 212,700,000
Amount of gross unrecognized tax benefits that would impact the effective tax rate, if recognized		236,800,000
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued		3,300,000	$ 2,000,000	$ 2,800,000
Domestic Country
Income Taxes [Line Items]
Operating Loss Carryforwards		222,700,000
Domestic Country | Research Tax Credit Carryforward
Income Taxes [Line Items]
Tax Credit Carryforward, Amount		116,200,000
State and Local Jurisdiction
Income Taxes [Line Items]
Operating Loss Carryforwards		258,900,000
State and Local Jurisdiction | Research Tax Credit Carryforward
Income Taxes [Line Items]
Tax Credit Carryforward, Amount		60,900,000
State and Local Jurisdiction and the Internal Revenue Service
Income Taxes [Line Items]
Valuation Allowance, Deferred Tax Asset, Change in Amount	$ 230,800,000
Deferred Tax Assets, Capital Loss Carryforwards		6,800,000
Foreign Country
Income Taxes [Line Items]
Deferred income taxes, net		9,200,000
Operating Loss Carryforwards		6,000,000
Tax Credit Carryforward, Amount		185,400,000
Foreign Country | Canada
Income Taxes [Line Items]
Tax Credit Carryforward, Amount		$ 50,400,000