Note 2 - Accounting Policies (Details Textual) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period	376
Income Tax Expense (Benefit)	$ 4,837	$ 4,740
Accounting Standards Update 2016-09 [Member]
Excess Tax Deduction Exceeding Related Share-based Compensation, Operating Activities	1,600
Income Tax Expense (Benefit)	$ (671)