Note 16 - Stock-based Compensation - Fair Value of Each Option Using Black-scholes Valuation Model Assumptions (Details)				12 Months Ended
	Nov. 03, 2015	Nov. 05, 2014	Feb. 11, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Risk-free interest rates				1.30%	1.40%	1.70%
Expected life (in years) (Year)				4 years 182 days	4 years	5 years 36 days
Dividend yield				1.10%	0.70%	0.90%
Expected volatility				30.70%	29.20%	35.10%
Chief Executive Officer [Member] | Options to Purchase 300,000 Shares of Common Stock [Member]
Risk-free interest rates				2.36%
Expected life (in years) (Year)				7 years 91 days
Dividend yield				0.90%
Expected volatility				42.80%
Chief Executive Officer [Member] | Options to Purchase 100,000 Shares of Common Stock [Member]
Risk-free interest rates				1.64%
Expected life (in years) (Year)				4 years 273 days
Dividend yield				0.90%
Expected volatility				33.10%
2012 Incentive Plan [Member] | Chief Financial Officer [Member]
Risk-free interest rates	1.35%	1.30%	0.81%
Expected life (in years) (Year)	4 years	4 years	3 years 136 days
Dividend yield	0.70%	0.70%	0.80%
Expected volatility	29.20%	32.40%	33.50%
Forfeiture rate	0.00%	0.00%	0.00%