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Note 15 - Share-Based and Other Compensation Plans (Employee Stock Purchase Plan) (Details) - Employee Stock Purchase Plan 2008 [Member] - Employee Stock Purchase Plan [Member] - shares
1 Months Ended 6 Months Ended 12 Months Ended
Jan. 31, 2018
Dec. 31, 2017
Jun. 30, 2017
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Employee Stock Ownership Plan (ESOP), Shares in ESOP   2,000,000   2,000,000    
Shares sold to employees under ESPP Plans       105,476 151,121 94,676
Share-based Compensation Arrangement by Share-based Payment Award, Discount from Market Price, Purchase Date       15.00%    
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]            
Expected life (months)   6 months 6 months 6 months    
Risk-free interest rate   1.35% 1.04%      
Volatility   29.37% 34.68%      
Dividend yield   0.06% 0.06%      
Subsequent Event [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Shares sold to employees under ESPP Plans 52,464          
Employee Stock Ownership Plan (ESOP), Number of Shares Available for Issuance 850,004