Note 6 - Fair Value Measurements (Details Textual) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Long-Term Debt	$ 1,195.3	$ 1,261.7
Fair Value, Nonrecurring [Member] | Senior Notes [Member]
Long-Term Debt	1,450.0	1,260.0
Long-Term Debt, Fair Value	$ 1,420.0	$ 1,240.0