Note 15 - Share Plans (Tables)

12 Months Ended

Dec. 31, 2018

Notes Tables

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

	201 8			201 7			201 6
Weighted average grant date fair value	$	17.86		$	16.84		$	13.77
Assumptions:
Expected stock price volatility		37	%		40	%		41	%
Risk free interest rate		2.60	%		1.92	%		1.31	%
Expected annual dividend per share	$	-		$	-		$	-
Expected life of options (years)		6.25			6.25			6.25

Share-based Compensation, Stock Options, Activity [Table Text Block]

	Number of Options			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value ($ in thousands)
Outstanding as of December 31, 2015A		2,128,014			15.15		7.7	$	40,271
Granted		398,313			33.24
Exercised		(995,469	)		2.89
Forfeited		(47,894	)		37.41
Outstanding as of December 31, 2016		1,482,964			27.49		7.5	$	23,840
Granted		346,421			40.13
Exercised		(287,375	)		10.58
Forfeited		(69,880	)		41.12
Outstanding as of December 31, 2017		1,472,130			33.11		7.3	$	25,281
Granted		366,231			43.88
Exercised		(267,909	)		19.90
Forfeited		(49,285	)		43.34
Outstanding as of December 31, 2018		1,521,167			37.70		7.0	$	19,212
Exercisable as of December 31, 2018		696,954			34.16		5.6	$	11,779

Schedule of Share-based Compensation, Restricted Stock Units Award Activity [Table Text Block]

	Shares			Weighted- Average Grant- Date Fair Value
Non-vested as of December 31, 2015		243,040			44.16
Granted		232,295			33.56
Vested		(95,858	)		41.93
Forfeited		(18,074	)		38.30
Non-vested as of December 31, 2016		361,403			38.18
Granted		211,769			39.91
Vested		(133,796	)		40.60
Forfeited		(47,100	)		42.48
Non-vested as of December 31, 2017		392,276			37.77
Granted		208,803			44.49
Vested		(128,433	)		39.03
Forfeited		(46,650	)		39.43
Non-vested as of December 31, 2018		425,996			40.50