Annual report [Section 13 and 15(d), not S-K Item 405]

Note 21 - Fair Value Measurement - Financial Assets and Financial Liabilities Carried at Fair Value on a Recurring Basis (Details)

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Note 21 - Fair Value Measurement - Financial Assets and Financial Liabilities Carried at Fair Value on a Recurring Basis (Details) - USD ($)
$ in Thousands
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Available for sale, fair value $ 1,161,400 $ 900,183  
US Treasury Securities [Member]      
Available for sale, fair value 617,486 340,807  
US Government Agencies Debt Securities [Member]      
Available for sale, fair value   215,485  
Collateralized Mortgage-Backed Securities [Member]      
Available for sale, fair value 219,274 10,223  
Corporate Debt Securities [Member]      
Available for sale, fair value $ 315,123 333,668  
Fair Value, Recurring [Member]      
Available for sale, fair value   1,161,400 $ 900,183
Total assets at fair value   1,161,400 900,183
Fair Value, Recurring [Member] | US Treasury Securities [Member]      
Available for sale, fair value   617,486 340,807
Fair Value, Recurring [Member] | US Government Agencies Debt Securities [Member]      
Available for sale, fair value   219,274 215,485
Fair Value, Recurring [Member] | Collateralized Mortgage-Backed Securities [Member]      
Available for sale, fair value   9,517 10,223
Fair Value, Recurring [Member] | Corporate Debt Securities [Member]      
Available for sale, fair value   315,123 333,668
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member]      
Available for sale, fair value   617,486 340,807
Total assets at fair value   617,486 340,807
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | US Treasury Securities [Member]      
Available for sale, fair value   617,486 340,807
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | US Government Agencies Debt Securities [Member]      
Available for sale, fair value   0 0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Collateralized Mortgage-Backed Securities [Member]      
Available for sale, fair value   0 0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member] | Corporate Debt Securities [Member]      
Available for sale, fair value   0 0
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member]      
Available for sale, fair value   543,914 552,516
Total assets at fair value   543,914 552,516
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | US Treasury Securities [Member]      
Available for sale, fair value   0 0
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | US Government Agencies Debt Securities [Member]      
Available for sale, fair value   219,274 215,485
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Collateralized Mortgage-Backed Securities [Member]      
Available for sale, fair value   9,517 10,223
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member] | Corporate Debt Securities [Member]      
Available for sale, fair value   315,123 326,808
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member]      
Available for sale, fair value   0 6,860
Total assets at fair value   0 6,860
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | US Treasury Securities [Member]      
Available for sale, fair value   0 0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | US Government Agencies Debt Securities [Member]      
Available for sale, fair value   0 0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Collateralized Mortgage-Backed Securities [Member]      
Available for sale, fair value   0 0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member] | Corporate Debt Securities [Member]      
Available for sale, fair value   $ 0 $ 6,860