Note 3 - Securities - Available-for-sale Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Due within 1 year, amortized cost	$ 205,633
Due within 1 year, fair value	205,367
Due after 1 but within 5 years, amortized cost	60,622
Due after 1 but within 5 years, fair value	60,113
Due after 5 but within 10 years, amortized cost	7,171
Due after 5 but within 10 years, fair value	7,091
Due after 10 years, amortized cost	98,259
Due after 10 years, fair value	97,429
Mortgage-backed securities – government agencies, amortized cost	138,768
Mortgage-backed securities – government agencies, fair value	137,131
Total securities available-for-sale, amortized cost	510,453	$ 443,742
Total securities available-for-sale, fair value	$ 507,131	$ 436,995

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=118942338&loc=SL82898722-210454

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 3
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Amount 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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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=118942338&loc=SL82898722-210454

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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