Note 5 - Income Taxes (Details Textual) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Tax Expense (Benefit)	$ 7,498	$ 5,443	$ 22,484	$ 21,784
Effective Income Tax Rate Reconciliation, Percent	30.30%	28.40%	26.10%	30.60%
Effective Income Tax Rate, Continuing Operations Before ASU Adoption			32.10%
Accounting Standards Update 2016-09 [Member]
Income Tax Expense (Benefit)			$ (5,114)
Effective Income Tax Rate Reconciliation, Percent			(6.00%)