Note 3 - Debt and Equity Securities - Debt and Equity Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Securities, Available-for-sale, Amortized Cost	$ 436,988	$ 295,683
Securities, Available-for-sale, Gross Unrealized Gains	1,992	41
Securities, Available-for-sale, Gross Unrealized Losses	2,003	10,472
Debt Securities, Available-for-sale, Total	436,977	285,252
US Government-sponsored Enterprises Debt Securities [Member]
Securities, Available-for-sale, Amortized Cost	66,723	71,446
Securities, Available-for-sale, Gross Unrealized Gains	18	0
Securities, Available-for-sale, Gross Unrealized Losses	224	2,979
Debt Securities, Available-for-sale, Total	66,517	68,467
Collateralized Mortgage Backed Securities [Member]
Securities, Available-for-sale, Amortized Cost	276,383	152,375
Securities, Available-for-sale, Gross Unrealized Gains	1,254	9
Securities, Available-for-sale, Gross Unrealized Losses	1,084	4,874
Debt Securities, Available-for-sale, Total	276,553	147,510
Asset-backed Securities [Member]
Securities, Available-for-sale, Amortized Cost	28,261	22,534
Securities, Available-for-sale, Gross Unrealized Gains	330	10
Securities, Available-for-sale, Gross Unrealized Losses	115	844
Debt Securities, Available-for-sale, Total	28,476	21,700
US States and Political Subdivisions Debt Securities [Member]
Securities, Available-for-sale, Amortized Cost	65,621	49,328
Securities, Available-for-sale, Gross Unrealized Gains	390	22
Securities, Available-for-sale, Gross Unrealized Losses	580	1,775
Debt Securities, Available-for-sale, Total	$ 65,431	$ 47,575

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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