Note 6 - Stock Based Compensation - Restricted Stock Awards Activity (Details) - Restricted Stock [Member] - $ / shares	6 Months Ended			12 Months Ended
	Jun. 30, 2017	Jun. 30, 2016		Dec. 31, 2016
Nonvested at beginning of year, weighted-average grant date fair value (in dollars per share)	$ 7.03	$ 6	[1]	$ 6	[1]
Nonvested at beginning of year, shares (in shares)	31,546	39,352		39,352
Nonvested at the end of the period, weighted-average grant date fair value (in dollars per share)	$ 8.23	$ 7.06	[1]	$ 7.03
Forfeited, weighted-average grant date fair value (in dollars per share)		$ 6.99
Granted, shares (in shares)	8,258	11,149
Granted, weighted-average grant date fair value (in dollars per share)	$ 9.87	$ 9.09	[1]	$ 9.09
Vested, shares (in shares)	(11,125)	(11,371)
Vested, weighted-average grant date fair value (in dollars per share)	$ 6.03	$ 5.44	[1]
Forfeited, shares (in shares)		(6,788)
Nonvested at the end of the period, shares (in shares)	28,679	32,342		31,546

[1] Restated for the 4% stock dividend distributed July 11, 2016.