Note 8 - Fair Value of Financial Instruments (Details Textual) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Revenue from Contract with Customer, Including Assessed Tax	$ 3,224,000	$ 2,036,000	$ 7,712,000	$ 5,625,000
Servicing Asset, Total	211,000,000.0		211,000,000.0		$ 201,700,000
Interest and Fee Income, Loans Held-for-sale, Mortgages	$ 248,000	142,000	$ 497,000	398,000
SBA Servicing Assets [Member]
Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets, Impact of 10 Percent Adverse Change in Key Assumptions, Percent	10.00%		10.00%		10.00%
Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets, Impact of 20 Percent Adverse Change in Key Assumptions	20.00%		20.00%		20.00%
Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Mortgages Held-for-sale, Fair Value Disclosure	$ 0		$ 0		$ 0
Servicing Fee Income [Member]
Revenue from Contract with Customer, Including Assessed Tax	$ 510,000	$ 498,000	$ 1,400,000	$ 1,400,000