Note 14 - Equity Incentive Plan - Summary of Exercisable Options and SAR's (Details)	12 Months Ended
	Dec. 31, 2020 $ / shares shares
Incentive Stock Options [Member]
Exercisable Options and SAR's outstanding (in shares) | shares	109,581
Exercisable Options and SAR's, Weighted Average Exercise Price (in dollars per share) | $ / shares	$ 45.43
Exercisable Options and SAR's, Weighted Average Remaining Term (Year)	6 years 6 months
Non-qualified Stock Options [Member]
Exercisable Options and SAR's outstanding (in shares) | shares	341,927
Exercisable Options and SAR's, Weighted Average Exercise Price (in dollars per share) | $ / shares	$ 41.63
Exercisable Options and SAR's, Weighted Average Remaining Term (Year)	4 years 6 months
Performance Shares [Member]
Exercisable Options and SAR's outstanding (in shares) | shares	11,210
Exercisable Options and SAR's, Weighted Average Exercise Price (in dollars per share) | $ / shares	$ 53.87
Exercisable Options and SAR's, Weighted Average Remaining Term (Year)	2 years 10 months 24 days