Financial Instruments - Available for Sale Securities (Detail) (USD $)	12 Months Ended
	Jan. 31, 2015	Jan. 31, 2014	Jan. 31, 2013
Derivative [Line Items]
Cost Method Investments	$ 52,600,000	$ 49,800,000
Other than Temporary Impairment Losses, Investments	19,200,000	0
Available-for-sale securities gross gains (losses)	700,000	(200,000)
Proceeds from Sale and Maturity of Marketable Securities	1,159,000,000	1,279,100,000
Notional amount of foreign currency forward contracts not designated as cash flow hedges	336,600,000	351,700,000
Net loss expected to be recognized into earnings	42,800,000	3,500,000	2,800,000
Foreign Exchange Contract
Derivative [Line Items]
Notional amount of foreign currency forward contracts not designated as cash flow hedges	$ 44,600,000	$ 205,500,000