(Gain) Loss on the Sale of Trade Receivables (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Jan. 31, 2012	Jan. 31, 2011	Jan. 31, 2010
Sale of Receivables [Line Items]
Total receivables sold	$ 30,307	$ 53,565	$ 34,009
Net proceeds	29,146	51,601	31,838
Discount on sold receivables	(1,161)	(1,964)	(2,171)
Unaccreted interest on sold receivables	1,273	2,133	1,549
Gain (loss) on sale of receivables	112	169	(622)
Trade accounts receivable
Sale of Receivables [Line Items]
Total receivables sold	13,645	27,011	14,557
Term Receivables
Sale of Receivables [Line Items]
Total receivables sold	$ 16,662	$ 26,554	$ 19,452