Note 4 - Fair Value Measurements - Assets Measured at Fair Value on Nonrecurring Basis (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended		12 Months Ended
		Sep. 30, 2020		Sep. 30, 2020		Dec. 31, 2019
Loans held for sale, Total gains (losses)		$ 24		$ 86		$ (40)
Loans (1), Total gains (losses)		12	[1]	50	[1]	(28)
Real estate, net (2), Total gains (losses)		0	[2]	0	[2]	0
Total, Total gains (losses)		36		136		(68)
Fair Value, Nonrecurring [Member]
Loans held for sale		7,225		7,225		3,606
Mortgage servicing rights		2,880		2,880		2,172
Mortgage servicing rights, Total gains (losses)		0		0		0
Loans (1)	[1]	2,881		2,881		3,126
Real estate, net (2)	[2]	414		414		580
Total		13,400		13,400		9,484
Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 1 [Member]
Loans held for sale		0		0		0
Mortgage servicing rights		0		0		0
Loans (1)	[1]	0		0		0
Real estate, net (2)	[2]	0		0		0
Total		0		0		0
Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 2 [Member]
Loans held for sale		7,225		7,225		3,606
Mortgage servicing rights		2,880		2,880		2,172
Loans (1)	[1]	2,881		2,881		3,126
Real estate, net (2)	[2]	414		414		580
Total		13,400		13,400		9,484
Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member]
Loans held for sale		0		0		0
Mortgage servicing rights		0		0		0
Loans (1)	[1]	0		0		0
Real estate, net (2)	[2]	0		0		0
Total		$ 0		$ 0		$ 0

[1] Represents the carrying value of loans for which adjustments are based on the appraised value of the collateral. The carrying value of loans fully charged-off is zero.

[2] Represents the fair value of foreclosed real estate and other collateral owned that were measured at fair value subsequent to their initial classification as foreclosed assets.