Note 3 - Financing Arrangements - Outstanding Borrowings (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Long-term debt	$ 1,326,107	$ 1,261,738
Less current portion of long-term debt	(249,961)	0
Total long-term debt	1,326,100	1,261,700
Senior Notes [Member]
Long-term debt	948,200	947,000
Revolving Credit Facility [Member]
Long-term debt	$ 627,900	$ 314,700