Note 2 - INVESTMENT SECURITIES - Amortized Cost and Fair Value of Investment Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Securities held to maturity:
Securities held to maturity, at amortized cost	$ 453,126	$ 476,165
Securities held to maturity, gross unrealized gains	38,312	45,360
Securities held to maturity, gross unrealized (losses)	(91)	(248)
Securities held to maturity, fair value	491,347	521,277
Allowance for credit losses HTM securities	174
Securities available for sale:
Debt Securities, Available-for-sale, Amortized Cost	340,726	350,060
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	8,956	12,430
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(2,809)	(524)
Debt Securities, Available-for-sale	346,873	361,966
Municipal securities
Securities held to maturity:
Securities held to maturity, at amortized cost	452,076	475,115
Securities held to maturity, gross unrealized gains	38,312	45,360
Securities held to maturity, gross unrealized (losses)	(91)	(248)
Securities held to maturity, fair value	490,297	520,227
Allowance for credit losses HTM securities	173
Securities available for sale:
Debt Securities, Available-for-sale, Amortized Cost	160,703	147,241
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	3,492	5,215
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(1,622)	(48)
Debt Securities, Available-for-sale	162,573	152,408
U.S. govt. sponsored agency securities
Securities available for sale:
Debt Securities, Available-for-sale, Amortized Cost	14,494	14,936
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	352	447
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(265)	(47)
Debt Securities, Available-for-sale	14,581	15,336
Residential mortgage-backed and related securities
Securities available for sale:
Debt Securities, Available-for-sale, Amortized Cost	115,230	127,670
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	3,742	5,510
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(920)	(338)
Debt Securities, Available-for-sale	118,052	132,842
Asset-backed securities
Securities available for sale:
Debt Securities, Available-for-sale, Amortized Cost	38,620	39,663
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	1,197	1,111
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(2)	(91)
Debt Securities, Available-for-sale	39,815	40,683
Other Securities
Securities held to maturity:
Securities held to maturity, at amortized cost	1,050	1,050
Securities held to maturity, fair value	1,050	1,050
Allowance for credit losses HTM securities	1
Securities available for sale:
Debt Securities, Available-for-sale, Amortized Cost	11,679	20,550
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	173	147
Debt Securities, Available-for-sale	$ 11,852	$ 20,697

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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