Note 17 - Stock-based Compensation - SARs Activity (Details) - Stock Appreciation Rights (SARs) [Member] - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Unvested (in shares)		731	704	735
Outstanding, aggregate intrinsic value	[1]	$ 8,422	$ 12,923	$ 21,443
Unvested, grant date weighted average cost (in dollars per share)		$ 3.83	$ 3.47	$ 3.26
Outstanding, weighted average remaining contractual life (Year)		5 years 3 months 18 days	5 years 2 months 12 days	5 years 1 month 6 days	5 years 6 months
Awarded (in shares)		53	100	46
Granted, aggregate intrinsic value	[1]	$ 213	$ 0	$ 0
Fair value at grant date (in dollars per share)		$ 6.24	$ 6.07	$ 6.34
Exercised (in shares)		(143)	(73)	(77)
Exercised, aggregate intrinsic value	[1]	$ 3,025	$ 1,654	$ 1,855
Exercised weighted average fair value (in dollars per share)		$ 3.47	$ 3.43	$ 3.18
Forfeited, exercise price (in dollars per share)		$ 0	$ 0	$ 0
Forfeited (in shares)		0	0
Unvested (in shares)		641	731	704	735
Outstanding, exercise price (in dollars per share)		$ 25.06
Outstanding, aggregate intrinsic value	[1]	$ 10,250	$ 8,422	$ 12,923	$ 21,443
Unvested, grant date weighted average cost (in dollars per share)		$ 4.10	$ 3.83	$ 3.47	$ 3.26
Vested and exercisable (in shares)		439
Vested and exercisable, aggregate intrinsic value	[1]	$ 9,017
Vested and exercisable, weighted average fair value (in dollars per share)		$ 3.42
Vested and exercisable, weighted average remaining contractual life (Year)		4 years
Unvested (in shares)		202
Unvested, aggregate intrinsic value	[1]	$ 1,233
Unvested, weighted average fair value (in dollars per share)		$ 5.59
Unvested, weighted average remaining contractual life (Year)		7 years 10 months 24 days
Vested during 2019 (in shares)		91
Vested, aggregate intrinsic value	[1]	$ 1,110
Vested, weighted average fair value (in dollars per share)		$ 4.66
Minimum [Member]
Outstanding, exercise price (in dollars per share)		14.02	14.02	14.02
Granted, exercise price (in dollars per share)		36.65	35.90	40.00
Exercised, exercise price (in dollars per share)		14.02	14.02	14.02
Outstanding, exercise price (in dollars per share)		14.02	14.02	14.02	14.02
Vested and exercisable, exercise price (in dollars per share)		14.02
Unvested, exercise price (in dollars per share)		22.96
Vested, exercise price (in dollars per share)		19.37
Maximum [Member]
Outstanding, exercise price (in dollars per share)		40.00	40.00	33.08
Granted, exercise price (in dollars per share)		38.18	39.32	40.00
Exercised, exercise price (in dollars per share)		22.96	19.37	17.89
Outstanding, exercise price (in dollars per share)		40.00	40.00	40.00	33.08
Vested and exercisable, exercise price (in dollars per share)		40.00
Unvested, exercise price (in dollars per share)		40.00
Vested, exercise price (in dollars per share)		40.00
Weighted Average [Member]
Outstanding, exercise price (in dollars per share)		22.42	19.51	17.78
Granted, exercise price (in dollars per share)		37.01	37.75	40.00
Exercised, exercise price (in dollars per share)		15.99	15.32	15.41
Forfeited, exercise price (in dollars per share)		0	0	0
Outstanding, exercise price (in dollars per share)		25.06	$ 22.42	$ 19.51	$ 17.78
Vested and exercisable, exercise price (in dollars per share)		20.53
Unvested, exercise price (in dollars per share)		34.93
Vested, exercise price (in dollars per share)		$ 28.80

[1] Intrinsic value for SARs is defined as the amount by which the current market price of the underlying stock exceeds the exercise or grant price.