Segment Reporting Revenues Related to Operations in Geographic Regions (Detail) - USD ($) $ in Thousands	3 Months Ended
Apr. 30, 2016	Apr. 30, 2015
Revenues:
Total revenues	$ 227,639	$ 272,143
UNITED STATES
Revenues:
Total revenues	83,220	129,191
Europe
Revenues:
Total revenues	54,874	46,319
Japan
Revenues:
Total revenues	37,932	21,417
Asia
Revenues:
Total revenues	48,967	70,129
Americas
Revenues:
Total revenues	$ 2,646	$ 5,087

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

Name:	us-gaap_Revenues
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration