Note 2 - Securities - Amortized Cost and Estimated Fair Value of Investment Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Securities available for sale, amortized cost	$ 341,504	$ 357,407
Investment securities available for sale, at fair value	344,212	364,296
Total investment securities,, held to maturity, amortized cost		357,407
Total mortgage-backed securities, held to maturity, fair value		364,296
Collateralized Mortgage Backed Securities [Member]
Due within one year, amortized cost	7,827
Due within one year, estimated fair value	7,832
Due within one year, held to maturity, amortized cost		80
Due within one year, held to maturity, fair value		84
Due after one through five years, amortized cost	24,347
Due after one through five years, estimated fair value	24,371
Due after one through five years, held to maturity, amortized cost		12,446
Due after one through five years, held to maturity, fair value		12,402
Due after five through ten years, amortized cost	8,466
Due after five through ten years, estimated fair value	8,391
Due after five through ten years, held to maturity, amortized cost		0
Due after five through ten years, held to maturity, fair value		0
Due after ten years, amortized cost	100,554
Due after ten years, estimated fair value	99,376
Due after ten years, held to maturity, amortized cost		75,791
Due after ten years, held to maturity, fair value		76,774
Securities available for sale, amortized cost	141,194
Investment securities available for sale, at fair value	139,970
Total investment securities,, held to maturity, amortized cost		88,317
Total mortgage-backed securities, held to maturity, fair value		89,260
Investment Securities, Excluding Mortgage Backed Securities [Member]
Due within one year, amortized cost	0
Due within one year, estimated fair value	0
Due within one year, held to maturity, amortized cost		0
Due within one year, held to maturity, fair value		0
Due after one through five years, amortized cost	6,391
Due after one through five years, estimated fair value	6,289
Due after one through five years, held to maturity, amortized cost		2,210
Due after one through five years, held to maturity, fair value		2,328
Due after five through ten years, amortized cost	79,679
Due after five through ten years, estimated fair value	80,807
Due after five through ten years, held to maturity, amortized cost		74,568
Due after five through ten years, held to maturity, fair value		74,351
Due after ten years, amortized cost	114,240
Due after ten years, estimated fair value	117,146
Due after ten years, held to maturity, amortized cost		192,312
Due after ten years, held to maturity, fair value		198,357
Securities available for sale, amortized cost	200,310
Investment securities available for sale, at fair value	$ 204,242
Total investment securities,, held to maturity, amortized cost		269,090
Total mortgage-backed securities, held to maturity, fair value		$ 275,036