Note 9 - Benefit Plans - Stock Option Activity (Details)	9 Months Ended
	Sep. 30, 2019 $ / shares shares
Balance outstanding, weighted average exercise price (in dollars per share) | $ / shares	$ 5.14
Granted, weighted average exercise price (in dollars per share) | $ / shares
Exercised, weighted average exercise price (in dollars per share) | $ / shares	5.16
Forfeited, weighted average exercise price (in dollars per share) | $ / shares
Balance outstanding, weighted average exercise price (in dollars per share) | $ / shares	5.08
Options exercisable, weighted average exercise price (in dollars per share) | $ / shares	$ 5.08
Incentive Stock Options [Member]
Balance outstanding (in shares)	12,500
Granted (in shares)
Exercised (in shares)	(9,000)
Forfeited (in shares)
Balance outstanding (in shares)	3,500
Options exercisable (in shares)	3,500
Non-Incentive Stock Options [Member]
Balance outstanding (in shares)	5,000
Granted (in shares)
Exercised (in shares)	(5,000)
Forfeited (in shares)
Balance outstanding (in shares)
Options exercisable (in shares)