Revenues Related to Operations in Geographic Regions (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Oct. 31, 2011	Oct. 31, 2010	Oct. 31, 2011	Oct. 31, 2010
Revenues:
Total revenues	$ 250,508	$ 238,937	$ 694,283	$ 607,448
North America
Revenues:
Total revenues	116,256	116,644	306,650	254,930
Europe
Revenues:
Total revenues	62,555	60,347	161,394	151,812
Japan
Revenues:
Total revenues	28,793	21,227	96,193	73,056
Pacific Rim
Revenues:
Total revenues	$ 42,904	$ 40,719	$ 130,046	$ 127,650