Note 9 - Equity Incentive Plans - Activity of Stock Option Incentive Plans (Details) - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Outstanding at beginning of year (in shares)	222,019	140,293	112,054
Outstanding at beginning of year, weighted average exercise price (in dollars per share)	$ 27.01	$ 41.68	$ 41.02
Granted (in shares)	0	165,879	36,394
Granted, weighted average exercise price (in dollars per share)		$ 12.45	$ 44.19
Forfeitures (in shares)	(10,000)	(84,153)	(8,155)
Forfeitures, weighted average exercise price (in dollars per share)	$ 12.55	$ 26.89	$ 42.55
Exercised (in shares)
Exercised, weighted average exercise price (in dollars per share)
Outstanding at end of year (in shares)	212,019	222,019	140,293
Outstanding at end of year, weighted average exercise price (in dollars per share)	$ 27.69	$ 27.01	$ 41.68
Exercisable shares and weighted average exercise price (in shares)	128,532	57,859	37,351
Exercisable shares and weighted average exercise price (in dollars per share)	$ 33.83	$ 42.05	$ 41.02
Director Plan 2011 [Member]
2011 Director Plan (in shares)	54,537	78,582	93,772
Omnibus Equity Incentive Plan 2010 [Member]
2011 Director Plan (in shares)			378,374
Omnibus Equity Incentive Plan 2014 [Member]
2011 Director Plan (in shares)	360,438	982,548