Note 8 - Shareholders' Equity - Information About Stock Options Granted (Details) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($) $ / shares shares
Options outstanding, range of exercise price, lower range (in dollars per share)	$ 40
Options outstanding, range of exercise price, upper range (in dollars per share)	$ 70
Options outstanding, number outstanding (in shares) | shares	973
Options outstanding, aggregate intrinsic value | $	$ 157
Options outstanding, weighted average remaining contractual life (Year)	6 years 6 months
Options outstanding, weighted average exercise price (in dollars per share)	$ 60
Options exercisable, number outstanding (in shares) | shares	614
Options exercisable, aggregate intrinsic value | $	$ 157
Options exercisable, weighted average remaining contractual life (Year)	5 years 4 months 24 days
Options exercisable, weighted average exercise price (in dollars per share)	$ 61
Range 1 [Member]
Options outstanding, range of exercise price, lower range (in dollars per share)	40
Options outstanding, range of exercise price, upper range (in dollars per share)	$ 45
Options outstanding, number outstanding (in shares) | shares	12
Options outstanding, aggregate intrinsic value | $	$ 149
Options outstanding, weighted average remaining contractual life (Year)	1 year 10 months 24 days
Options outstanding, weighted average exercise price (in dollars per share)	$ 42
Options exercisable, number outstanding (in shares) | shares	12
Options exercisable, aggregate intrinsic value | $	$ 149
Options exercisable, weighted average remaining contractual life (Year)	1 year 10 months 24 days
Options exercisable, weighted average exercise price (in dollars per share)	$ 42
Range 2 [Member]
Options outstanding, range of exercise price, lower range (in dollars per share)	45
Options outstanding, range of exercise price, upper range (in dollars per share)	50
Range 3 [Member]
Options outstanding, range of exercise price, lower range (in dollars per share)	50
Options outstanding, range of exercise price, upper range (in dollars per share)	$ 55
Options outstanding, number outstanding (in shares) | shares	4
Options outstanding, aggregate intrinsic value | $	$ 8
Options outstanding, weighted average remaining contractual life (Year)	1 month 6 days
Options outstanding, weighted average exercise price (in dollars per share)	$ 53
Options exercisable, number outstanding (in shares) | shares	4
Options exercisable, aggregate intrinsic value | $	$ 8
Options exercisable, weighted average remaining contractual life (Year)	1 month 6 days
Options exercisable, weighted average exercise price (in dollars per share)	$ 53
Range 4 [Member]
Options outstanding, range of exercise price, lower range (in dollars per share)	55
Options outstanding, range of exercise price, upper range (in dollars per share)	$ 60
Options outstanding, number outstanding (in shares) | shares	572
Options outstanding, aggregate intrinsic value | $	$ 0
Options outstanding, weighted average remaining contractual life (Year)	7 years 7 months 6 days
Options outstanding, weighted average exercise price (in dollars per share)	$ 57
Options exercisable, number outstanding (in shares) | shares	213
Options exercisable, aggregate intrinsic value | $	$ 0
Options exercisable, weighted average remaining contractual life (Year)	6 years 1 month 6 days
Options exercisable, weighted average exercise price (in dollars per share)	$ 58
Range 5 [Member]
Options outstanding, range of exercise price, lower range (in dollars per share)	60
Options outstanding, range of exercise price, upper range (in dollars per share)	$ 65
Options outstanding, number outstanding (in shares) | shares	247
Options outstanding, weighted average remaining contractual life (Year)	4 years 7 months 6 days
Options outstanding, weighted average exercise price (in dollars per share)	$ 62
Options exercisable, number outstanding (in shares) | shares	247
Options exercisable, weighted average remaining contractual life (Year)	4 years 7 months 6 days
Options exercisable, weighted average exercise price (in dollars per share)	$ 62
Range 6 [Member]
Options outstanding, range of exercise price, lower range (in dollars per share)	65
Options outstanding, range of exercise price, upper range (in dollars per share)	$ 70
Options outstanding, number outstanding (in shares) | shares	138
Options outstanding, weighted average remaining contractual life (Year)	6 years 1 month 6 days
Options outstanding, weighted average exercise price (in dollars per share)	$ 66
Options exercisable, number outstanding (in shares) | shares	138
Options exercisable, weighted average remaining contractual life (Year)	6 years 1 month 6 days
Options exercisable, weighted average exercise price (in dollars per share)	$ 66