Note 3 - Investment Securities - Amortized Cost and Fair Value of Investment Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Due In One Year or Less, amortized cost
Due In One Year or Less, fair value
Due After One Year Through Five Years, amortized cost	4,142
Due After One Year Through Five Years, fair value	4,147
Due After Five Years Through Ten Years, amortized cost	1,135
Due After Five Years Through Ten Years, fair value	1,167
Due After Ten Years, amortized cost	1,104
Due After Ten Years, fair value	1,117
Amortized cost with single maturity date	6,381
Fair value with single maturity date	6,431
Mortgage-Backed Securities, amortized cost	403,165
Mortgage-Backed Securities, fair value	403,408
Amortized cost	409,546	$ 363,433
Fair Value	$ 409,839	$ 353,066

Amortized cost of 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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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in second through fifth fiscal year following latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.

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Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in second through fifth fiscal year following latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.

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