Quarterly report pursuant to Section 13 or 15(d)

Note 6 - Stock-based Compensation - Estimated Fair Value of Stock Options Assumptions (Details)

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Note 6 - Stock-based Compensation - Estimated Fair Value of Stock Options Assumptions (Details) - $ / shares
9 Months Ended 12 Months Ended
Dec. 31, 2017
Jan. 01, 2017
Apr. 02, 2017
Number of options issued (in shares) 140,000 120,000  
December 18, 2017 [Member]      
Number of options issued (in shares) 10,000    
Grant date Dec. 18, 2017    
Dividend yield 4.92%    
Expected volatility 25.00%    
Risk free interest rate 1.94%    
Contractual term (years) (Year) 10 years    
Expected term (years) (Year) 3 years    
Forfeiture rate 5.00%    
Exercise price (grant-date closing price) per option (in dollars per share) $ 6.50    
Fair value per option (in dollars per share) $ 0.59    
August 4 2017 [Member]      
Number of options issued (in shares) 20,000    
Grant date Aug. 04, 2017    
Dividend yield 5.77%    
Expected volatility 25.00%    
Risk free interest rate 1.51%    
Contractual term (years) (Year) 10 years    
Expected term (years) (Year) 3 years    
Forfeiture rate 5.00%    
Exercise price (grant-date closing price) per option (in dollars per share) $ 5.55    
Fair value per option (in dollars per share) $ 0.50    
June 8 2017 [Member]      
Number of options issued (in shares) 110,000    
Grant date Jun. 08, 2017    
Dividend yield 4.13%    
Expected volatility 25.00%    
Risk free interest rate 1.47%    
Contractual term (years) (Year) 10 years    
Expected term (years) (Year) 3 years    
Forfeiture rate 5.00%    
Exercise price (grant-date closing price) per option (in dollars per share) $ 7.75    
Fair value per option (in dollars per share) $ 0.85    
June 8, 2016 [Member]      
Number of options issued (in shares)     120,000
Grant date     Jun. 08, 2016
Dividend yield     3.33%
Expected volatility     20.00%
Risk free interest rate     0.93%
Contractual term (years) (Year)     10 years
Expected term (years) (Year)     3 years
Forfeiture rate     5.00%
Exercise price (grant-date closing price) per option (in dollars per share)     $ 9.60
Fair value per option (in dollars per share)     $ 0.94