Note 13 - Accounting for Stock-based Compensation - Stock Options Outstanding, by Exercise Price Range (Details)	12 Months Ended
	Dec. 31, 2016 $ / shares shares
Range of Exercise Prices, Lower range (in dollars per share)	$ 9.05
Range of Exercise Prices, Upper range (in dollars per share)	$ 41
Number Outstanding (in Shares) (in shares) | shares	587,407
Weighted Average Remaining Contractual Term (Year)	5 years 255 days
Weighted Average Exercise Price (in dollars per share)	$ 29.56
Number Exercisable (in Shares) (in shares) | shares	535,376
Exercisable Weighted Average Exercise Price (in dollars per share)	$ 28.47
Price Range 1 [Member]
Range of Exercise Prices, Lower range (in dollars per share)	9.05
Range of Exercise Prices, Upper range (in dollars per share)	$ 25
Number Outstanding (in Shares) (in shares) | shares	131,267
Weighted Average Remaining Contractual Term (Year)	3 years 255 days
Weighted Average Exercise Price (in dollars per share)	$ 23.37
Number Exercisable (in Shares) (in shares) | shares	131,267
Exercisable Weighted Average Exercise Price (in dollars per share)	$ 23.37
Price Range 2 [Member]
Range of Exercise Prices, Lower range (in dollars per share)	25.01
Range of Exercise Prices, Upper range (in dollars per share)	$ 28
Number Outstanding (in Shares) (in shares) | shares	300,107
Weighted Average Remaining Contractual Term (Year)	5 years 292 days
Weighted Average Exercise Price (in dollars per share)	$ 26.48
Number Exercisable (in Shares) (in shares) | shares	300,107
Exercisable Weighted Average Exercise Price (in dollars per share)	$ 26.48
Price Range 3 [Member]
Range of Exercise Prices, Lower range (in dollars per share)	28.01
Range of Exercise Prices, Upper range (in dollars per share)	$ 41
Number Outstanding (in Shares) (in shares) | shares	156,033
Weighted Average Remaining Contractual Term (Year)	7 years 36 days
Weighted Average Exercise Price (in dollars per share)	$ 40.68
Number Exercisable (in Shares) (in shares) | shares	104,002
Exercisable Weighted Average Exercise Price (in dollars per share)	$ 40.68