Annual report pursuant to Section 13 and 15(d)

Note 23 - Fair Value Measurement - Financial Assets and Financial Liabilities Carried at Fair Value on a Recurring Basis (Details)

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Note 23 - Fair Value Measurement - Financial Assets and Financial Liabilities Carried at Fair Value on a Recurring Basis (Details) - USD ($)
$ in Thousands
Dec. 31, 2017
Dec. 31, 2016
Available-for-sale securities $ 538,080 $ 422,375
US Treasury and Government [Member]    
Available-for-sale securities 55,356 46,254
Collateralized Mortgage Backed Securities [Member]    
Available-for-sale securities 276,498 227,190
US States and Political Subdivisions Debt Securities [Member]    
Available-for-sale securities 134,849 139,930
Corporate Debt Securities [Member]    
Available-for-sale securities 71,377 9,001
Fair Value, Measurements, Recurring [Member]    
Available-for-sale securities 538,080 422,375
Fair Value, Measurements, Recurring [Member] | US Treasury and Government [Member]    
Available-for-sale securities 55,356 46,254
Fair Value, Measurements, Recurring [Member] | Collateralized Mortgage Backed Securities [Member]    
Available-for-sale securities 276,498 227,190
Fair Value, Measurements, Recurring [Member] | US States and Political Subdivisions Debt Securities [Member]    
Available-for-sale securities 134,849 139,930
Fair Value, Measurements, Recurring [Member] | Corporate Debt Securities [Member]    
Available-for-sale securities 71,377 9,001
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]    
Available-for-sale securities
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | US Treasury and Government [Member]    
Available-for-sale securities
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Collateralized Mortgage Backed Securities [Member]    
Available-for-sale securities
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | US States and Political Subdivisions Debt Securities [Member]    
Available-for-sale securities
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Corporate Debt Securities [Member]    
Available-for-sale securities
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]    
Available-for-sale securities 531,580 422,375
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | US Treasury and Government [Member]    
Available-for-sale securities 55,356 46,254
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Collateralized Mortgage Backed Securities [Member]    
Available-for-sale securities 276,498 227,190
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | US States and Political Subdivisions Debt Securities [Member]    
Available-for-sale securities 134,849 139,930
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Corporate Debt Securities [Member]    
Available-for-sale securities 64,877 9,001
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]    
Available-for-sale securities 6,500
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | US Treasury and Government [Member]    
Available-for-sale securities
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Collateralized Mortgage Backed Securities [Member]    
Available-for-sale securities
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | US States and Political Subdivisions Debt Securities [Member]    
Available-for-sale securities
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Corporate Debt Securities [Member]    
Available-for-sale securities $ 6,500