Note 3 - Investment Securities - Held to Maturity Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Securities held-to-maturity, carrying value	$ 548,191	$ 0
Securities held-to-maturity, gains	24
Securities held-to-maturity, losses	(12,408)
Debt Securities, Held-to-Maturity, Fair Value, Total	535,807	0
Held to maturity debt securities (fair value of $535,807 in 2022 and $0 in 2021, respectively)	548,191	0
Held to maturity debt securities, fair value	535,807	$ 0
US Treasury Securities and US Government Agencies Debt Securities [Member]
Securities held-to-maturity, carrying value	277,491
Securities held-to-maturity, gains	0
Securities held-to-maturity, losses	(1,922)
Debt Securities, Held-to-Maturity, Fair Value, Total	275,569
Held to maturity debt securities (fair value of $535,807 in 2022 and $0 in 2021, respectively)	277,491
Held to maturity debt securities, fair value	275,569
US Government-sponsored Enterprises Debt Securities [Member]
Securities held-to-maturity, carrying value	27,996
Securities held-to-maturity, gains	17
Securities held-to-maturity, losses	(195)
Debt Securities, Held-to-Maturity, Fair Value, Total	27,818
Held to maturity debt securities (fair value of $535,807 in 2022 and $0 in 2021, respectively)	27,996
Held to maturity debt securities, fair value	27,818
Mortgage-Backed Securities, Issued by US Government Sponsored Enterprises [Member]
Securities held-to-maturity, carrying value	242,704
Securities held-to-maturity, gains	7
Securities held-to-maturity, losses	(10,291)
Debt Securities, Held-to-Maturity, Fair Value, Total	232,420
Held to maturity debt securities (fair value of $535,807 in 2022 and $0 in 2021, respectively)	242,704
Held to maturity debt securities, fair value	232,420
US States and Political Subdivisions Debt Securities [Member]
Securities held-to-maturity, carrying value	0
Securities held-to-maturity, gains	0
Securities held-to-maturity, losses	0
Debt Securities, Held-to-Maturity, Fair Value, Total	0
Held to maturity debt securities (fair value of $535,807 in 2022 and $0 in 2021, respectively)	0
Held to maturity debt securities, fair value	0
Other Debt Obligations [Member]
Securities held-to-maturity, carrying value	0
Securities held-to-maturity, gains	0
Securities held-to-maturity, losses	0
Debt Securities, Held-to-Maturity, Fair Value, Total	0
Held to maturity debt securities (fair value of $535,807 in 2022 and $0 in 2021, respectively)	0
Held to maturity debt securities, fair value	$ 0

Amount, before allowance for credit loss, of investment in debt security measured at amortized cost (held-to-maturity).

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 45
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-URI https://asc.fasb.org/extlink&oid=124255206&loc=SL82895884-210446

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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