Change in Allowance for Doubtful Accounts (Detail) (USD $) In Thousands, unless otherwise specified					3 Months Ended
	Apr. 30, 2014	Jan. 31, 2014	Apr. 30, 2013	Jan. 31, 2013	Apr. 30, 2014 Allowance for Doubtful Accounts [Member]	Apr. 30, 2013 Allowance for Doubtful Accounts [Member]
Allowance for doubtful accounts receivable, current	$ 3,484	$ 5,469	$ 4,752	$ 5,331
Valuation Allowances and Reserves, Charged to Cost and Expense					(1,744)	(500)
Net Deductions Recoveries					$ (241)	$ (79)