Note 13 - Stock-based Compensation (Details Textual) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Expense (Benefit), Total	$ (1,972)	$ (199)	$ 11,835
Allocated Share-based Compensation Expense, Total	$ 21,507	$ 24,143	$ 13,277
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Number of Shares, Ending Balance	1,999,069	2,372,682
Share-based Compensation Arrangement by Share-based Payment Award, Option, Nonvested, Weighted Average Exercise Price, Ending Balance	$ 7.27	$ 6.39
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value	7.52	7.66	$ 5.55
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested, Weighted Average Grant Date Fair Value	6.18
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested Options Forfeited, Weighted Average Grant Date Fair Value	$ 6.86	$ 5.24	$ 6.26
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period	2,017,442	172,326	510,512
Proceeds from Stock Options Exercised	$ 38,362	$ 2,720	$ 2,940
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value	27,600	500	6,300
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Stock Options	5,500
Employee Stock Option [Member]
Income Tax Expense (Benefit), Total	9,100	4,000	4,100
Allocated Share-based Compensation Expense, Total	$ 9,600	10,300	6,900
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	328 days
Restricted Stock Units (RSUs) [Member]
Allocated Share-based Compensation Expense, Total	$ 11,900	13,800	6,400
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	317 days
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number, Ending Balance	1,259,003
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Share-based Awards Other than Options	$ 9,200
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value	$ 9,900	$ 9,500	$ 6,800
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value	$ 17.06	$ 15.39	$ 18.64
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value	$ 17.31	$ 15.37	$ 16.95