Financial Instruments - Available for Sale Securities (Detail) (USD $)	12 Months Ended
	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2012
Derivative [Line Items]
Other than Temporary Impairment Losses, Investments	$ 0	$ 10,500,000
Available-for-sale securities gross gains (losses)	(200,000)	5,000,000
Proceeds from Sale and Maturity of Marketable Securities	1,279,100,000	1,097,700,000
Notional amount of foreign currency forward contracts not designated as cash flow hedges	351,700,000	359,800,000
Net loss expected to be recognized into earnings	3,500,000	2,800,000	9,200,000
Foreign Exchange Contract
Derivative [Line Items]
Notional amount of foreign currency forward contracts not designated as cash flow hedges	$ 205,500,000	$ 78,400,000