Note 1 - Summary of Significant Accounting Policies - Supplemental Disclosure of Cash Flow Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Transactions Related to Capital Additions not Settled in Cash	$ 37,429	$ 13,757
Cash Paid During the Year for:
Interest (net of amount capitalized)	30,132	28,109	$ 29,791
Income Taxes	$ 4,797	$ 6,109	$ 5,064