Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Apr. 30, 2012	Jan. 31, 2012	Apr. 30, 2011
Condensed Consolidated Balance Sheets [Abstract]
Allowance for doubtful accounts receivable	$ 31,480	$ 34,436	$ 23,972
Preferred stock, shares authorized	1,000,000	1,000,000	1,000,000
Preferred stock, shares issued
Preferred stock, shares outstanding
Common stock, par value	$ 0.01	$ 0.01	$ 0.01
Common stock, shares authorized	80,000,000	80,000,000	40,000,000
Common stock, shares issued	20,461,840	20,279,132	20,188,889
Treasury stock, shares	492,225	492,225	367,225