Note 2 - Investment Securities - Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Due within one year, AFS, amortized cost	$ 117,105
Due within one year, AFS, fair value	112,410
Due within one year, HTM, carrying value	51,077
Due within one year, HTM, fair value	50,188
Due after one year but within five years, AFS, amortized cost	54,505
Due after one year but within five years, AFS, fair value	50,972
Due after one year but within five years, HTM, carrying value	153,800
Due after one year but within five years, HTM, fair value	147,004
Due after five years but within 10 years, AFS, amortized cost	79,708
Due after five years but within 10 years, AFS, fair value	66,296
Due after five years but within 10 years, HTM, carrying value	25,660
Due after five years but within 10 years, HTM, fair value	22,176
Due after 10 years, AFS, amortized cost	130,179
Due after 10 years, AFS, fair value	117,904
Due after 10 years, HTM, carrying value	574
Due after 10 years, HTM, fair value	562
Mortgage-backed securities – government agencies, AFS, amortized cost	814,224
Mortgage-backed securities – government agencies, AFS, fair value	672,666
Mortgage backed securities - government agencies, HTM, carrying value	214,094
Mortgage backed securities - government agencies, HTM, fair value	177,488
Total available for sale debt securities, amortized cost	1,195,721	$ 1,297,977
Total available for sale debt securities, fair value	1,020,248	1,144,617
Total held to maturity debt securities, carrying value	445,205
Total held to maturity debt securities, fair value	$ 397,418	$ 431,833