Note 5 - Loans and Allowance for Loan Losses (Details Textual) xbrli-pure in Thousands	3 Months Ended
Mar. 31, 2019 USD ($)	Mar. 31, 2018	Dec. 31, 2018 USD ($)
Financing Receivable, Troubled Debt Restructuring, Subsequent Default, Number of Contracts	0	0
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Carrying Amount, Net	$ 3,098,000		$ 3,173,000
Substandard [Member]
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Carrying Amount, Net	3,100,000
Troubled Debt Restructuring [Member]
Financing Receivable, Allowance for Credit Loss, Ending Balance	$ 888,761		$ 901,086

The recorded balance, net of any applicable reductions (for example, unamortized accretable yield and allowance for loan losses). This relates to loans not accounted for debt securities with evidence of deterioration of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

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- Definition

Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement.

+ References

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-Publisher FASB
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- Definition

Number of financing receivable contracts modified as troubled debt restructuring within previous 12 months, with subsequent payment default.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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