Note 3 - Available for Sale Debt Securities - Available-for-sale Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Due within one year, amortized cost	$ 30,408
Due within one year, fair value	30,442
Due after one year but within five years, amortized cost	100,808
Due after one year but within five years, fair value	100,774
Due after five years but within 10 years, amortized cost	28,165
Due after five years but within 10 years, fair value	28,220
Due after 10 years, amortized cost	135,976
Due after 10 years, fair value	138,990
Mortgage-backed securities – government agencies, amortized cost	777,636
Mortgage-backed securities – government agencies, fair value	771,722
Total available for sale debt securities	1,072,993	$ 574,722
Total available for sale debt securities	$ 1,070,148	$ 586,978

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=123581744&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=124258926&loc=SL82898722-210454

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