Derivative Instruments and Hedging Activities - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jul. 31, 2011 Contract Person	Jul. 31, 2010 Person Contract
Derivative [Line Items]
Number of new foreign currency forward contracts entered during period	692	664
Number of new foreign currency forward contracts outstanding	30	45
Notional amount of foreign currency derivatives entered into during period outstanding	$ 132,634	$ 156,044
Cash flow forwards | Cash Flow Hedging | Other expense, net
Derivative [Line Items]
Gain (Loss) Recognized in Income on Derivatives (Ineffective Portion and Amount Excluded from Effectiveness Testing)	52	33
Cash Flow Hedging
Derivative [Line Items]
Gain (Loss) Recognized in Income on Derivatives (Ineffective Portion and Amount Excluded from Effectiveness Testing)	$ 52	$ 33