Note 7 - Fair Value Measurements - Level 3 Fair Value Measurements (Details)	6 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2016
Impaired loans [Member] | Present Value of Cash Flows [Member] | Minimum [Member]
Discount rate	6.75%	6.75%
Impaired loans [Member] | Present Value of Cash Flows [Member] | Maximum [Member]
Discount rate	8.00%	8.00%
Impaired loans [Member] | Present Value of Cash Flows [Member] | Weighted Average [Member]
Discount rate	7.36%	7.35%
Other Real Estate Owned [Member] | Discounted Appraised Value [Member] | Minimum [Member]
Selling cost	1.79%	2.91%
Discount rate	1.41%	0.00%
Other Real Estate Owned [Member] | Discounted Appraised Value [Member] | Maximum [Member]
Selling cost	11.09%	8.60%
Discount rate	53.46%	53.46%
Other Real Estate Owned [Member] | Discounted Appraised Value [Member] | Weighted Average [Member]
Selling cost	4.91%	6.48%
Discount rate	9.34%	13.66%