Note 8 - Stock-based Compensation - Stock Option Activity (Details) - $ / shares	6 Months Ended	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Jun. 30, 2015	Jun. 30, 2014
Outstanding, shares (in shares)	43,000	40,000		12,333
Weighted-average exercise price per share, outstanding (in dollars per share)	$ 8.70	$ 9.49	$ 8.70	$ 9.42	$ 17.34
Weighted-average remaining contractual term, outstanding (Year)	47 years 343 days	6 years 156 days		48 years 197 days	25 years 313 days
Granted, shares (in shares)	0	0	0	33,333
Weighted-average exercise price per share, granted (in dollars per share)				$ 7.50
Forfeited or expired, shares (in shares)	(3,000)	(16,667)		(2,666)
Weighted-average exercise price per share, forfeited or expired (in dollars per share)	$ 18.60	$ 7.62		$ 22.26
Outstanding, shares (in shares)	40,000	23,333	40,000	43,000	12,333
Exercisable, shares (in shares)		23,333
Weighted-average exercise price per share, exercisable (in dollars per share)		$ 9.49
Weighted-average remaining contractual term, exercisable (Year)		6 years 156 days