Note 9 - Stock-based Compensation - Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Balance, number of shares (in shares)	0	5,000
Balance, weighted average exercise price per share (in dollars per share)	$ 0	$ 10.30
Balance, weighted average fair value at grant date (in dollars per share)		$ 0	$ 0
Balance, weighted average remaining contractual life (Year)	4 years 273 days	0 years	182 days
Balance, intrinsic value	$ 0	$ 0
Options granted, number of shares (in shares)	60,000	0
Options granted, weighted average exercise price per share (in dollars per share)	$ 8	$ 0
Options granted, intrinsic value		$ 0
Options exercised, number of shares (in shares)	0	0
Options exercised, weighted average exercise price per share (in dollars per share)	$ 0	$ 0
Options exercised, intrinsic value	$ 0	$ 0
Options expired, number of shares (in shares)	0	(5,000)
Options expired, weighted average exercise price per share (in dollars per share)	$ 0	$ (10.30)
Options expired, weighted average fair value at grant date (in dollars per share)		$ 0
Options expired, intrinsic value	$ 0	$ 0
Options granted, weighted average remaining contractual life (Year)
Balance, number of shares (in shares)	60,000	0	5,000
Balance, weighted average exercise price per share (in dollars per share)	$ 8	$ 0	$ 10.30
Balance, intrinsic value		$ 0	$ 0