Note 11 - Share-based Compensation - Stock Options Outstanding and Exercisable (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Lower exercise price range (in dollars per share)	$ 6.79
Upper exercise price range (in dollars per share)	$ 7.33
Number of options outstanding (in shares)	1,300,000	1,300,000
Options outstanding weighted average remaining contractual life (Year)	273 days
Options outstanding weighted average exercise price (in dollars per share)	$ 6.85	$ 6.85
Options outstanding aggregate intrinsic value
Number of options vested and exercisable (in shares)	1,300,000
Options vested and exercisable weighted average remaining contractual life (Year)	273 days
Options vested and exercisable weighted average exercise price (in dollars per share)	$ 6.85
Options vested and exercisable aggregate intrinsic value