Note 3 - Investment Securities - Investment Securities Continuous Unrealized Loss Position (Details) $ in Thousands	Sep. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)
Number of investment positions - less than twelve months, available for sale	137	278
Fair value - less than twelve months, available for sale	$ 81,023	$ 181,760
Gross unrealized losses - less than twelve months, available for sale	$ 5,034	$ 10,821
Number of investment positions - more than twelve months, available for sale	337	187
Fair value - more than twelve months, available for sale	$ 356,577	$ 258,858
Gross unrealized losses - more than twelve months, available for sale	$ 44,075	$ 36,023
Number of investment positions, available for sale	474	465
Fair value, available for sale	$ 437,600	$ 440,618
Gross unrealized losses, available for sale	49,109	$ 46,844
Number of investment positions - less than twelve months, held to maturity		3
Fair value - less than twelve months, held to maturity		$ 3,779
Gross unrealized losses - less than twelve months, held to maturity		1,221
Fair value - more than twelve months, held to maturity	4,472	1,532
Gross unrealized losses - more than twelve months, held to maturity	$ 2,528	$ 468
Number of investment positions, held to maturity	4	4
Fair value, held to maturity	$ 4,472	$ 5,311
Gross unrealized losses, held to maturity	$ 2,528	$ 1,689
Agency Collateralized Mortgage Obligations [Member]
Number of investment positions - less than twelve months, available for sale	7	23
Fair value - less than twelve months, available for sale	$ 17,601	$ 6,287
Gross unrealized losses - less than twelve months, available for sale	$ 246	$ 336
Number of investment positions - more than twelve months, available for sale	23	3
Fair value - more than twelve months, available for sale	$ 5,214	$ 257
Gross unrealized losses - more than twelve months, available for sale	$ 378	$ 13
Mortgage-Backed Securities, Issued by US Government Sponsored Enterprises [Member]
Number of investment positions - less than twelve months, available for sale	97	69
Fair value - less than twelve months, available for sale	$ 72,073	$ 27,561
Gross unrealized losses - less than twelve months, available for sale	$ 12,312	$ 2,214
Number of investment positions - more than twelve months, available for sale		28
Fair value - more than twelve months, available for sale		$ 56,303
Gross unrealized losses - more than twelve months, available for sale		$ 8,979
US Government Agencies Debt Securities [Member]
Number of investment positions - less than twelve months, available for sale	6	15
Fair value - less than twelve months, available for sale	$ 5,210	$ 35,079
Gross unrealized losses - less than twelve months, available for sale	$ 108	$ 1,314
Number of investment positions - more than twelve months, available for sale	55	45
Fair value - more than twelve months, available for sale	$ 129,035	$ 102,902
Gross unrealized losses - more than twelve months, available for sale	$ 12,095	$ 11,848
US States and Political Subdivisions Debt Securities [Member]
Number of investment positions - less than twelve months, available for sale	124	154
Fair value - less than twelve months, available for sale	$ 58,212	$ 81,218
Gross unrealized losses - less than twelve months, available for sale	$ 4,680	$ 5,960
US Treasury and Government [Member]
Number of investment positions - less than twelve months, available for sale	27	17
Fair value - less than twelve months, available for sale	$ 73,714	$ 31,615
Gross unrealized losses - less than twelve months, available for sale	$ 2,813	$ 997
Number of investment positions - more than twelve months, available for sale		13
Fair value - more than twelve months, available for sale		$ 47,117
Gross unrealized losses - more than twelve months, available for sale		$ 2,917
Municipal Notes [Member]
Number of investment positions - more than twelve months, available for sale	135	98
Fair value - more than twelve months, available for sale	$ 76,541	$ 52,279
Gross unrealized losses - more than twelve months, available for sale	$ 16,477	$ 12,266
Corporate Note Securities [Member]
Number of investment positions - less than twelve months, held to maturity	4	3
Fair value - less than twelve months, held to maturity	$ 4,472	$ 3,779
Gross unrealized losses - less than twelve months, held to maturity	$ 2,528	$ 1,221
Number of investment positions - more than twelve months, held to maturity	4	1
Fair value - more than twelve months, held to maturity		$ 1,532
Gross unrealized losses - more than twelve months, held to maturity		$ 468