Note 17 - Share Plans - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Outstanding, number of options (in shares)	1,521,167	1,472,130	1,482,964
Outstanding, weighted average exercise price (in dollars per share)	$ 37.70	$ 33.11	$ 27.49
Outstanding, weighted average remaining contractual term (Year)	6 years 10 months 24 days	7 years	7 years 3 months 18 days	7 years 6 months
Outstanding, aggregate intrinsic value	$ 93,242	$ 19,212	$ 25,281	$ 23,840
Granted, number of options (in shares)	369,779	366,231	346,421
Granted, weighted average exercise price (in dollars per share)	$ 52.07	$ 43.88	$ 40.13
Exercised, number of options (in shares)	(263,250)	(267,909)	(287,375)
Exercised, weighted average exercise price (in dollars per share)	$ 30.75	$ 19.90	$ 10.58
Forfeited, number of options (in shares)	(35,010)	(49,285)	(69,880)
Forfeited, weighted average exercise price (in dollars per share)	$ 43.79	$ 43.34	$ 41.12
Outstanding, number of options (in shares)	1,592,686	1,521,167	1,472,130	1,482,964
Outstanding, weighted average exercise price (in dollars per share)	$ 42.04	$ 37.70	$ 33.11	$ 27.49
Exercisable, number of options (in shares)	726,817
Exercisable, weighted average exercise price (in dollars per share)	$ 37.78
Exercisable, weighted average remaining contractual term (Year)	5 years 3 months 18 days
Exercisable, aggregate intrinsic value	$ 45,649