v3.26.1
Note 4 - Investments and Fair Value Measurements - Long-term Debt (Details) - Fair Value, Inputs, Level 2 [Member] - USD ($)
$ in Millions
Jun. 30, 2026
Dec. 31, 2025
Reported Value Measurement [Member]    
Senior notes (Note 6) $ 4,207.6 $ 4,715.4
Estimate of Fair Value Measurement [Member]    
Senior notes (Note 6) $ 4,067.6 $ 4,670.6