Note 13 - Share-based Compensation - Stock Option Activity (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Balance (in shares)	26,000
Balance (in dollars per share)	$ 24.97
Options granted (in shares)
Options granted (in dollars per share)
Options exercised (in shares)	0	0
Options exercised (in dollars per share)
Options canceled (in shares)	(2,000)
Options canceled (in dollars per share)	$ 34.77
Balance (in shares)	24,000	26,000
Balance (in dollars per share)	$ 24.15	$ 24.97
Balance (Year)
Balance
Exercisable, December 31, 2017 (in shares)	24,000
Exercisable, December 31, 2017 (in dollars per share)	$ 24.15
Exercisable, December 31, 2017 (Year)	2 years 87 days
Exercisable, December 31, 2017