Note 1 - Basis of Presentation and Summary of Significant Accounting Policies (Details Textual) $ in Thousands	1 Months Ended	3 Months Ended	12 Months Ended
	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Jan. 01, 2020 USD ($)	May 01, 2019	Jan. 01, 2019 USD ($)
Repayments of Subordinated Debt, Total			$ 3,609	$ (0)	$ (0)
Number of Operating Segments			2
Allowance for Loan and Lease Losses, Period Increase (Decrease), Total		$ 2,000
Cash Reserve Deposit Required and Made			$ 11,000
Operating Lease, Right-of-Use Asset			$ 12,737	$ 0
Accounting Standards Update 2016-02 [Member]
Operating Lease, Right-of-Use Asset								$ 17,000
Operating Lease, Liability, Total								$ 18,000
Minimum [Member]
Property, Plant and Equipment, Useful Life			3 years
Minimum [Member] | Accounting Standards Update 2016-13 [Member] | Subsequent Event [Member]
Debt Securities, Available-for-sale, Allowance for Credit Loss, Ending Balance						$ 7,500
Maximum [Member]
Property, Plant and Equipment, Useful Life			40 years
Maximum [Member] | Accounting Standards Update 2016-13 [Member] | Subsequent Event [Member]
Debt Securities, Available-for-sale, Allowance for Credit Loss, Ending Balance						$ 8,500
Subordinated Notes Assumed in the king Acquisition [Member]
Repayments of Subordinated Debt, Total	$ 4,000
KBST [Member]
Noncontrolling Interest, Ownership Percentage by Parent							100.00%