Stock Option Plans (Details 1) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Jan. 31, 2013
Company's stock option activity
Outstanding, beginning shares	1,413
Granted, shares	172
Exercised, shares	(158)
Forfeited, shares
Expired, shares
Outstanding, ending shares	1,427
Exercisable, shares	1,316
Vested and expected to vest, shares	1,424
Weighted Average Exercise Price, Outstanding beginning	$ 9.60
Weighted Average Exercise Price, Granted	$ 18.21
Weighted Average Exercise Price, Exercised	$ 2.10
Weighted Average Exercise Price, Forfeited
Weighted Average Exercise Price, Expired
Weighted Average Exercise Price, Outstanding ending	$ 11.37
Weighted Average Exercise Price, Exercisable	$ 10.94
Weighted Average Exercise Price, Vested and expected to vest	$ 11.44
Weighted Average Remaining Contractual Term, outstanding	5 years 2 months 23 days
Weighted Average Remaining Contractual Term, exercisable	4 years 10 months 17 days
Weighted Average Remaining Contractual Term, Vested and expected to vest	5 years 2 months 12 days
Aggregate Intrinsic Value, Outstanding	$ 6,192
Aggregate Intrinsic Value, Exercisable	6,158
Aggregate Intrinsic Value, Vested and expected to vest	$ 6,192