Note 11 - Equity Incentive Plan - Performance Stock Units (Details) - Performance Shares [Member]	3 Months Ended
	Mar. 31, 2022 $ / shares shares
Outstanding, shares (in shares) | shares	158,297
Outstanding, weighted average grant date fair value (in dollars per share) | $ / shares	$ 37.44
Performance factor adjustment (in shares) | shares	2,125
Performance factor adjustment (in dollars per share) | $ / shares	$ 32.53
Vested, shares (in shares) | shares	(19,125)
Vested, weighted average grant date fair value (in dollars per share) | $ / shares	$ 32.53
Forfeited and cancelled, shares (in shares) | shares	(23,400)
Forfeited and cancelled, weighted average grant date fair value (in dollars per share) | $ / shares	$ 41.86
Outstanding, shares (in shares) | shares	117,897
Outstanding, weighted average grant date fair value (in dollars per share) | $ / shares	$ 34.98