Note 12 - Equity Incentive Plans and Employee Benefits - Black-scholes Option Valuation Model Assumptions (Details) - $ / shares	12 Months Ended
	Jan. 28, 2017	Jan. 30, 2016	Jan. 31, 2015
Weighted average fair value (in dollars per share)	$ 3.14	$ 3.64	$ 1.80
Employee Stock Option [Member]
Expected volatility	50.77%	44.84%	42.72%
Risk-free interest rate	1.27%	1.60%	1.63%
Expected term (in years) (Year)	5 years 83 days	5 years 69 days	5 years 40 days
Dividend yield	0.00%	0.00%	0.00%
Weighted average fair value (in dollars per share)	$ 3.14	$ 3.64	$ 1.80
Employee Stock Purchase Plan [Member]
Expected volatility	57.19%	77.90%	50.05%
Risk-free interest rate	0.50%	0.44%	0.08%
Expected term (in years) (Year)	182 days	167 days	182 days
Dividend yield	0.00%	0.00%	0.00%
Weighted average fair value (in dollars per share)	$ 1.91	$ 2.24	$ 1.67