Note 14 - Stock-based Compensation - Options Outstanding (Details)	12 Months Ended
	Dec. 31, 2016 $ / shares shares
Options outstanding (in shares) | shares	177,959
Weighted average exercise price (in dollars per share)	$ 55.48
Weighted average remaining contractual life in years (Year)	2 years 255 days
Exercise Price Range 1 [Member]
Options outstanding (in shares) | shares	90,000
Exercise prices, lower range limit (in dollars per share)	$ 44.80
Exercise prices, upper range limit (in dollars per share)	52.93
Weighted average exercise price (in dollars per share)	$ 49.07
Weighted average remaining contractual life in years (Year)	1 year 182 days
Exercise Price Range 2 [Member]
Options outstanding (in shares) | shares	87,959
Exercise prices, lower range limit (in dollars per share)	$ 61.25
Exercise prices, upper range limit (in dollars per share)	62.78
Weighted average exercise price (in dollars per share)	$ 62.03
Weighted average remaining contractual life in years (Year)	3 years 328 days