Note 5 - Mortgage Servicing Rights - Fair Value of Servicing Rights (Details)	Dec. 31, 2019	Dec. 31, 2018
Measurement Input, Discount Rate [Member]
Discount rate	0.12	0.12
Measurement Input, Prepayment Rate [Member] | Minimum [Member]
Discount rate	1.1	0.83
Measurement Input, Prepayment Rate [Member] | Maximum [Member]
Discount rate	2.46	2.26
Measurement Input, Weighted Average Prepayment Rate [Member]
Discount rate	1.71	1.19