Note 2 - Investment Securities - Amortized Cost and Fair Value of Debt Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Securities available for sale, amortized cost, due in one year or less	$ 2,499
Securities available for sale, fair value, due in one year or less	2,521
Securities held to maturity, amortized cost, due in one year or less	0
Securities held to maturity, fair value, due in one year or less	0
Securities available for sale, amortized cost, due after one year through five years	100,545
Securities available for sale, fair value, due after one year through five years	101,059
Securities held to maturity, amortized cost, due after one year through five years	0
Securities held to maturity, fair value, due after one year through five years	0
Securities available for sale, amortized cost, due after five years through ten years	62,222
Securities available for sale, fair value, due after five years through ten years	63,681
Securities held to maturity, amortized cost, due after five years through ten years	0
Securities held to maturity, fair value, due after five years through ten years	0
Securities available for sale, amortized cost, due after ten years	84,859
Securities available for sale, fair value, due after ten years	87,632
Securities held to maturity, amortized cost, due after ten years	2,000
Securities held to maturity, fair value, due after ten years	2,025
Securities available for sale, amortized cost, single maturity	250,125
Securities available for sale, fair value, single maturity	254,893
Securities held to maturity, amortized cost, single maturity	2,000
Securities held to maturity, fair value, single maturity	2,025
Mortgage-backed securities and CMO, available for sale, amortized cost	97,613
Mortgage-backed securities and CMO, available for sale, fair value	98,589
Mortgage-backed securities and CMO, held to maturity, amortized cost	0
Mortgage-backed securities and CMO, held to maturity, fair value	0
Securities available for sale, amortized cost	347,738	$ 274,709
Securities available for sale, fair value	353,482	283,502
Securities held to maturity, amortized cost	2,000	$ 0
Securities held to maturity, fair value	$ 2,025