Segment Reporting Revenues Related to Operations in Geographic Regions (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2015	Jul. 31, 2014	Jul. 31, 2015	Jul. 31, 2014
Revenues:
Total revenues	$ 281,062	$ 260,233	$ 553,205	$ 512,384
UNITED STATES
Revenues:
Total revenues	115,598	111,692	244,789	236,458
Europe
Revenues:
Total revenues	69,520	55,462	115,839	115,611
Japan
Revenues:
Total revenues	15,524	20,973	36,941	42,254
Asia
Revenues:
Total revenues	77,458	62,963	147,587	106,676
Americas [Member]
Revenues:
Total revenues	$ 2,962	$ 9,143	$ 8,049	$ 11,385