Quarterly Financial Data (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Jan. 31, 2013	Oct. 31, 2012	Jul. 31, 2012	Apr. 30, 2012	Jan. 31, 2012	Oct. 31, 2011	Jul. 31, 2011	Apr. 30, 2011	Jan. 31, 2013	Jan. 31, 2012	Jan. 31, 2011
Schedule of Quarterly financial Data (Unaudited)
Net revenues:	$ 28,401	$ 18,574	$ 23,080	$ 34,630	$ 37,034	$ 28,020	$ 21,278	$ 26,502	$ 104,685	$ 112,834	$ 71,363
Gross profit:	8,773	4,353	7,400	16,887	21,269	14,345	8,213	13,925	37,413	57,752	26,642
Income (loss) before income taxes:	3,365	(2,178)	1,274	11,063	14,645	9,056	2,168	8,461	13,524	34,330	6,794
Incomes taxes (benefit):	(50)	(956)	(5,128)	2,607	4,480	2,293	868	2,368	(3,527)	10,009	2,065
Net income (loss):	$ 3,415	$ (1,222)	$ 6,402	$ 8,456	$ 10,165	$ 6,763	$ 1,300	$ 6,093	$ 17,051	$ 24,321	$ 4,729
Income per common share - basic:	$ 0.27	$ (0.10)	$ 0.51	$ 0.67	$ 0.82	$ 0.55	$ 0.12	$ 0.61	$ 1.34	$ 2.13	$ 0.48
Income per common share - diluted:	$ 0.26	$ (0.09)	$ 0.48	$ 0.63	$ 0.77	$ 0.52	$ 0.11	$ 0.58	$ 1.29	$ 2.02	$ 0.46