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Note 2 - Securities - Schedule of Maturities of Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Less than 1 Year	$ 40,428
1 Year - 5 Years	221,258
5 Years - 10 Years	683,387
More than 10 Years	91,461
Fair Value	1,028,115	$ 574,787
Equity securities	8,419	2,896
Fair value	1,036,534	577,683
US Treasury and Government [Member]
Less than 1 Year	2,020
1 Year - 5 Years	0
5 Years - 10 Years	0
More than 10 Years	0
Fair Value	$ 2,020	2,051
Less than 1 year, weighted average yield	1.98%
1 year to 5 years, weighted average yield	0.00%
5 years to 10 years , weighted average yields	0.00%
More than 10 years , weighted average yields	0.00%
Weighted average yields, total	1.98%
US Treasury Securities [Member]
Less than 1 Year	$ 2,033
1 Year - 5 Years	0
5 Years - 10 Years	90,753
More than 10 Years	0
Fair Value	$ 92,786	2,056
Less than 1 year, weighted average yield	1.85%
1 year to 5 years, weighted average yield	0.00%
5 years to 10 years , weighted average yields	1.16%
More than 10 years , weighted average yields	0.00%
Weighted average yields, total	1.18%
US States and Political Subdivisions Debt Securities [Member]
Less than 1 Year	$ 18,807
1 Year - 5 Years	58,342
5 Years - 10 Years	337,206
More than 10 Years	82,383
Fair Value	$ 496,738	320,368
Less than 1 year, weighted average yield	2.80%
1 year to 5 years, weighted average yield	2.86%
5 years to 10 years , weighted average yields	2.50%
More than 10 years , weighted average yields	2.33%
Weighted average yields, total	2.52%
Corporate Debt Securities [Member]
Less than 1 Year	$ 507
1 Year - 5 Years	828
5 Years - 10 Years	10,678
More than 10 Years	1,000
Fair Value	$ 13,013	3,589
Less than 1 year, weighted average yield	2.50%
1 year to 5 years, weighted average yield	3.50%
5 years to 10 years , weighted average yields	2.80%
More than 10 years , weighted average yields	3.75%
Weighted average yields, total	2.90%
Asset-backed Securities [Member]
Less than 1 Year	$ 0
1 Year - 5 Years	12,691
5 Years - 10 Years	4,171
More than 10 Years	0
Fair Value	$ 16,862	0
Less than 1 year, weighted average yield	0.00%
1 year to 5 years, weighted average yield	0.64%
5 years to 10 years , weighted average yields	0.76%
More than 10 years , weighted average yields	0.00%
Weighted average yields, total	0.67%
Collateralized Mortgage Backed Securities [Member]
Less than 1 Year	$ 17,061
1 Year - 5 Years	148,397
5 Years - 10 Years	240,579
More than 10 Years	659
Fair Value	$ 406,696	246,723
Less than 1 year, weighted average yield	1.69%
1 year to 5 years, weighted average yield	1.58%
5 years to 10 years , weighted average yields	1.38%
More than 10 years , weighted average yields	2.90%
Weighted average yields, total	1.47%
Debt Securities [Member]
Less than 1 Year	$ 23,367
1 Year - 5 Years	71,861
5 Years - 10 Years	442,808
More than 10 Years	83,383
Fair Value	621,419	$ 328,064
Equity Securities [Member]
Less than 1 Year	0
1 Year - 5 Years	1,000
5 Years - 10 Years	0
More than 10 Years	$ 7,419
Less than 1 year, weighted average yield	0.00%
1 year to 5 years, weighted average yield	3.69%
5 years to 10 years , weighted average yields	0.00%
More than 10 years , weighted average yields	0.00%
Weighted average yields, total	0.44%

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