Note 7 - Stock-based Compensation - Restricted Stock Units (Details)	6 Months Ended
	Jun. 30, 2023 $ / shares shares
Time-based Restricted Stock Units [Member]
Balance (in shares) | shares	202,059
Balance, weighted-average grant date fair value (in dollars per share) | $ / shares	$ 33.29
Granted (in shares) | shares	813
Granted, weighted-average grant date fair value (in dollars per share) | $ / shares	$ 36.87
Vested (in shares) | shares	(1,660)
Vested, weighted-average grant date fair value (in dollars per share) | $ / shares	$ 33.68
Forfeited (in shares) | shares	(1,395)
Forfeited, weighted-average grant date fair value (in dollars per share) | $ / shares	$ 42.12
Balance (in shares) | shares	199,817
Balance, weighted-average grant date fair value (in dollars per share) | $ / shares	$ 33.24
Performance-based Restricted Stock Units [Member]
Balance (in shares) | shares	362,965
Balance, weighted-average grant date fair value (in dollars per share) | $ / shares	$ 31.56
Granted (in shares) | shares	0
Granted, weighted-average grant date fair value (in dollars per share) | $ / shares	$ 0
Vested (in shares) | shares	(136,808)
Vested, weighted-average grant date fair value (in dollars per share) | $ / shares	$ 34.21
Forfeited (in shares) | shares	0
Forfeited, weighted-average grant date fair value (in dollars per share) | $ / shares	$ 0
Balance (in shares) | shares	226,157
Balance, weighted-average grant date fair value (in dollars per share) | $ / shares	$ 29.96