Note 8 - Equity Incentive Plans and Equity - Restricted Stock Units Award Activity (Details)	12 Months Ended
	Dec. 31, 2021 $ / shares shares
Restricted Stock Units (RSUs) [Member]
Balance (in shares) | shares	170
Balance, weighted average grant date fair value (in dollars per share) | $ / shares	$ 43.60
Granted (in shares) | shares	47
Granted, weighted average grant date fair value (in dollars per share) | $ / shares	$ 152.27
Exercised/Vested (in shares) | shares	(109)
Exercised/Vested, weighted average grant date fair value (in dollars per share) | $ / shares	$ 38.64
Forfeited (in shares) | shares	(6)
Forfeited, weighted average grant date fair value (in dollars per share) | $ / shares	$ 92.25
Balance (in shares) | shares	103
Balance, weighted average grant date fair value (in dollars per share) | $ / shares	$ 96.18
Performance Based Restricted Stock Units [Member]
Balance (in shares) | shares	23
Balance, weighted average grant date fair value (in dollars per share) | $ / shares	$ 55.54
Granted (in shares) | shares	0
Granted, weighted average grant date fair value (in dollars per share) | $ / shares	$ 0
Forfeited (in shares) | shares	(1)
Forfeited, weighted average grant date fair value (in dollars per share) | $ / shares	$ 111.65
Balance (in shares) | shares	22
Balance, weighted average grant date fair value (in dollars per share) | $ / shares	$ 111.65