Note 10 - Stock-based Compensation - RSUs Activity (Details) - Restricted Stock Units (RSUs) [Member] shares in Thousands	9 Months Ended
	Oct. 31, 2017 $ / shares shares
Outstanding at January 31, 2017 (in shares) | shares	623
Outstanding at January 31, 2017 (in dollars per share) | $ / shares	$ 20.56
Granted (in shares) | shares	294
Granted, weighted average grant date fair value (in dollars per share) | $ / shares	$ 30.68
Released (in shares) | shares	(245)	[1]
Released, weighted average grant date fair value (in dollars per share) | $ / shares	$ 20.44	[1]
Forfeited (in shares) | shares	(10)
Forfeited, weighted average grant date fair value (in dollars per share) | $ / shares	$ 20.99
Outstanding at October 31, 2017 (in shares) | shares	662
Outstanding at October 31, 2017 (in dollars per share) | $ / shares	$ 25.07

[1] The number of RSUs released includes shares withheld on behalf of employees to satisfy the minimum statutory tax withholding requirements.