Note 2 - Stock-Based Compensation (Details) - Valuation Assumptions, Stock Purchase Rights (Employee Stock Purchase Plan [Member])	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Employee Stock Purchase Plan [Member]
Note 2 - Stock-Based Compensation (Details) - Valuation Assumptions, Stock Purchase Rights [Line Items]
Expected term (years)	6 months	6 months
Expected volatility	33.90%	28.50%
Risk-free interest rate	0.10%	0.10%