Note 6 - Stock-based Compensation - Fair Value of Stock-based Award Using Exercise Multiple-based Lattice SAR and RSU Pricing Model Assumptions (Details) - Stock Appreciation Rights and Restricted Stock Units [Member] - The 2018 Incentive Plan [Member]	Jun. 25, 2018	May 08, 2018
Director and Chief Executive Officer [Member]
Risk-free interest rate		2.84%
Expected life (in years) (Year)		5 years 182 days
Dividend yield		0.79%
Expected volatility		25.24%
Forfeiture rate		0.00%
Sub-Optimal Exercise Factor		2.5
Employees and Senior Management [Member]
Risk-free interest rate	2.79%
Expected life (in years) (Year)	6 years
Dividend yield	0.92%
Expected volatility	25.64%
Employees [Member]
Forfeiture rate	2.78%
Sub-Optimal Exercise Factor	2
Senior Management [Member]
Forfeiture rate	0.00%
Sub-Optimal Exercise Factor	2.8