Note 11 - Stock Awards - Stock Option Activity (Details) - $ / shares	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Outstanding, beginning of period (in shares)	318,000	272,550
Outstanding, beginning of period, average exercise price (in dollars per share)	$ 9.43	$ 8.21
Granted (in shares)	62,150	64,600
Granted, average exercise price (in dollars per share)	$ 11.71	$ 14.11
Exercised (in shares)		16,650
Exercised, average exercise price (in dollars per share)		$ 8.15
Expired (in shares)
Expired, average exercise price (in dollars per share)	$ 0	$ 0
Forfeited (in shares)	450
Forfeited, average exercise price (in dollars per share)	$ 11.71	$ 0
Options outstanding, end of period (in shares)	379,700	320,500
Options outstanding, end of period, average exercise price (in dollars per share)	$ 9.80	$ 9.41
Options exercisable, end of period (in shares)	248,300	210,633
Options exercisable, end of period, average exercise price (in dollars per share)	$ 8.71	$ 8.20