Note 2 - Stock-Based Compensation (Details) - Valuation Assumptions, Stock Purchase Rights (Employee Stock Purchase Plan [Member])	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 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	6 months	6 months
Expected volatility	25.10%	27.50%	29.50%	28.00%
Risk-free interest rate	0.10%	0.10%	0.10%	0.10%
Dividend yield	1.40%		0.70%