Accounting Policies and Basis of Presentation - Supplemental Cash Flow Information (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Oct. 31, 2013	Oct. 31, 2012
Cash Flow Supplemental Disclosures [Line Items]
Income taxes	$ 6,854	$ 12,745
Interest	2,912	2,073
Noncash investing and financing activities:
Preferred units received in SolmeteX, LLC	432
Accrued capital additions	439	1,837
Deferred convertible notes offering fees	891
Capital lease obligations for equipment		$ 35