Note 3 - Supplemental Income Statement and Cash Flow Disclosure - Supplemental Disclosures of Cash Flow Information and Non-cash Investing and Financing Activities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Interest, net of interest capitalized	$ 685	$ 726	$ 637
Income taxes	$ 56,476	$ 30,157	$ 49,830