Note 4 - Financing Arrangements - Outstanding Borrowings (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Long-term debt	$ 1,366,506	$ 1,326,107
Less current portion of long-term debt	0	(249,961)
Total long-term debt	1,366,500	1,326,100
Senior Notes [Member]
Long-term debt	698,400	948,200
Revolving Credit Facility [Member]
Long-term debt	$ 668,100	$ 627,900