Financing Arrangements - Long-term debt (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Financing Arrangements
Less debt issuance costs (deduction from debt liability)	$ (3.0)	$ (1.7)
Total long-term debt	197.0	298.3
Principal payments during each of the next five years and thereafter
2025	0.0
2026	0.0
2027	0.0
2028	0.0
2029	200.0
Line of Credit due July 2029
Financing Arrangements
Total debt	$ 200.0	$ 300.0