Note 10 - Financial Instruments - Assets Recorded at Fair Value on a Nonrecurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Impaired Loans [Member]
Assets at fair value	$ 189	$ 199
Fair Value, Nonrecurring [Member]
Assets at fair value	189	199
Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 1 [Member]
Assets at fair value	0	0
Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 2 [Member]
Assets at fair value	0	0
Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member]
Assets at fair value	189	199
Fair Value, Nonrecurring [Member] | Impaired Loans [Member]
Assets at fair value	189	199
Fair Value, Nonrecurring [Member] | Impaired Loans [Member] | Fair Value, Inputs, Level 1 [Member]
Assets at fair value	0	0
Fair Value, Nonrecurring [Member] | Impaired Loans [Member] | Fair Value, Inputs, Level 2 [Member]
Assets at fair value	0	0
Fair Value, Nonrecurring [Member] | Impaired Loans [Member] | Fair Value, Inputs, Level 3 [Member]
Assets at fair value	$ 189	$ 199