Note 5 - Stock-based Compensation - RSUs Activity (Details) - Restricted Stock Units (RSUs) [Member] - $ / shares		12 Months Ended
		Jan. 31, 2017	Jan. 31, 2016	Jan. 31, 2015
Restricted stock (in shares)		617	503	430
Restricted stock, weighted average grant date fair value (in dollars per share)		$ 20.91	$ 16.27	$ 11.02
Granted (in shares)		307	326	287
Granted, weighted average grant date fair value (in dollars per share)		$ 18.54	$ 24.75	$ 21.25
Released (in shares)	[1]	(259)	(192)	(167)
Released, weighted average grant date fair value (in dollars per share)	[1]	$ 18.96	$ 15.58	$ 11.92
Forfeited (in shares)		(42)	(20)	(47)
Forfeited, weighted average grant date fair value (in dollars per share)		$ 20.69	$ 18.93	$ 14
Restricted stock (in shares)		623	617	503
Restricted stock, weighted average grant date fair value (in dollars per share)		$ 20.56	$ 20.91	$ 16.27

[1] The number of RSUs released includes shares withheld on behalf of employees to satisfy minimum statutory tax withholding requirements. During the fiscal years ended January 31, 2017, 2016 and 2015, the Company withheld 75,000 shares, 52,000 shares and 45,000 shares, respectively, for payment of these taxes. The value of the withheld shares for the fiscal years ended January 31, 2017, 2016 and 2015 were $1.5 million, $1.4 million and $1.0 million, respectively.