Note 7 - Fair Value Measurements - Level 3 Fair Value Measurements (Details) - Valuation, Market Approach [Member]		Sep. 30, 2020	Dec. 31, 2019
Measurement Input, Discount Rate [Member] | Minimum [Member]
Discount rate	[1]	0.0550	0.0550
Discount rate	[1]	(0.0550)	(0.0550)
Measurement Input, Discount Rate [Member] | Maximum [Member]
Discount rate	[1]	0.0650	0.0650
Discount rate	[1]	(0.0650)	(0.0650)
Measurement Input, Discount Rate [Member] | Weighted Average [Member]
Discount rate	[1]	0.0578	0.0577
Discount rate	[1]	(0.0578)	(0.0577)
Measurement Input, Cost to Sell [Member] | Maximum [Member]
Level 3 Fair Value Measurements	[2]	0.0554	0.0600
Level 3 Fair Value Measurements	[2]	(0.0554)	(0.0600)
Measurement Input, Cost to Sell [Member] | Weighted Average [Member]
Level 3 Fair Value Measurements	[2]	0.0046	0.0068
Level 3 Fair Value Measurements	[2]	(0.0046)	(0.0068)
Measurement Input, Discount for Lack of Marketability and Age of Appraisal [Member] | Minimum [Member]
Level 3 Fair Value Measurements	[2]	0.0000	0.0000
Level 3 Fair Value Measurements	[2]	(0.0000)	(0.0000)
Measurement Input, Discount for Lack of Marketability and Age of Appraisal [Member] | Maximum [Member]
Level 3 Fair Value Measurements	[2]	0.1135	0.4517
Level 3 Fair Value Measurements	[2]	(0.1135)	(0.4517)
Measurement Input, Discount for Lack of Marketability and Age of Appraisal [Member] | Weighted Average [Member]
Level 3 Fair Value Measurements	[2]	0.0095	0.0128
Level 3 Fair Value Measurements	[2]	(0.0095)	(0.0128)

[1] Unobservable inputs were weighted by the relative fair value of the impaired loans.

[2] Discounts were weighted by the relative appraised value of the OREO properties.