STOCK-BASED COMPENSATION - Summary of Activity under Company's Stock Option Plans (Details 2) - $ / shares	6 Months Ended		12 Months Ended
	Jul. 31, 2015	Jul. 31, 2014	Jan. 31, 2015	Jan. 31, 2014
STOCK-BASED COMPENSATION
Shares, Outstanding, Beginning balance	876,350	916,150	916,150
Shares, Granted	135,000	180,500
Shares, Exercised	(59,450)	(153,800)
Shares, Forfeited	(6,000)
Shares, Outstanding, Ending balance	945,900	942,850	876,350	916,150
Shares, Exercisable	685,900	540,350
Weighted Average Exercise Price, Outstanding, Beginning balance	$ 22.34	$ 17.36	$ 17.36
Weighted Average Exercise Price, Granted	33.62	27.09
Weighted Average Exercise Price, Exercised	16.82	14.84
Weighted Average Exercise Price, Forfeited	17.33
Weighted Average Exercise Price, Outstanding, Ending balance	24.33	19.63	$ 22.34	$ 17.36
Weighted Average Exercise Price, Exercisable	$ 20.85	$ 15.67
Weighted Average Remaining Term, Outstanding	7 years 2 months 12 days	6 years 7 months 24 days	7 years 29 days	6 years 15 days
Weighted Average Remaining Term, Exercisable	6 years 7 months 6 days	5 years 11 months 1 day
Weighted Average Fair Value, Outstanding	$ 6.53	$ 5.72	$ 6.01	$ 5.58
Weighted Average Fair Value, Exercisable	$ 5.71	$ 5.91