Note 7 - Share-based Compensation - Restricted Stock Unit Activity (Details) - Restricted Stock Units (RSUs) [Member]	9 Months Ended
	Sep. 30, 2022 $ / shares shares
Outstanding, restricted stock units (in shares) | shares	101,168
Outstanding, weighted average award date fair value (in dollars per share) | $ / shares	$ 41.78
Awarded, restricted stock units (in shares) | shares	51,981
Awarded, weighted average award date fair value (in dollars per share) | $ / shares	$ 74.94
Shares vested, restricted stock units (in shares) | shares	(49,575)
Shares vested, weighted average award date fair value (in dollars per share) | $ / shares	$ 41.05
Shares forfeited (in shares) | shares	(947)
Shares forfeited (in dollars per share) | $ / shares	$ 64.32
Outstanding, restricted stock units (in shares) | shares	102,627
Outstanding, weighted average award date fair value (in dollars per share) | $ / shares	$ 55.29