Revenues Related to Operations in Geographic Regions (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jul. 31, 2012	Jul. 31, 2011	Jul. 31, 2012	Jul. 31, 2011
Revenues:
Total revenues	$ 240,811	$ 213,740	$ 488,729	$ 443,775
North America
Revenues:
Total revenues	101,553	100,071	230,663	190,394
Europe
Revenues:
Total revenues	53,964	46,642	106,595	98,839
Japan
Revenues:
Total revenues	38,181	25,766	63,164	67,400
Pacific Rim
Revenues:
Total revenues	$ 47,113	$ 41,261	$ 88,307	$ 87,142