Note 10 - Stock-based Compensation - RSUs Activity (Details) - Restricted Stock Units (RSUs) [Member] shares in Thousands	6 Months Ended
	Jul. 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	293
Granted, weighted average grant date fair value (in dollars per share) | $ / shares	$ 30.66
Released (in shares) | shares	(235)	[1]
Released, weighted average grant date fair value (in dollars per share) | $ / shares	$ 20.48	[1]
Outstanding at July 31, 2017 (in dollars per share) | $ / shares	$ 24.98
Forfeited (in shares) | shares	(8)
Forfeited, weighted average grant date fair value (in dollars per share) | $ / shares	$ 20.17
Outstanding at July 31, 2017 (in shares) | shares	673

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