Revenues Related to Operations in Geographic Regions (Detail) (USD $) In Thousands	3 Months Ended				6 Months Ended
	Jul. 31, 2011	Apr. 30, 2011	Jul. 31, 2010	Apr. 30, 2010	Jul. 31, 2011	Jul. 31, 2010
Revenues:
Total revenues	$ 213,740	$ 230,035	$ 187,934	$ 180,577	$ 443,775	$ 368,511
North America
Revenues:
Total revenues	100,071		73,121		190,394	138,286
Europe
Revenues:
Total revenues	46,642		48,888		98,839	91,465
Japan
Revenues:
Total revenues	25,766		20,161		67,400	51,829
Pacific Rim
Revenues:
Total revenues	$ 41,261		$ 45,764		$ 87,142	$ 86,931