Derivatives and Financial Instruments - Recorded Amounts and Estimated Fair Values of Long-term Debt and Derivative Financial Instruments (Detail) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Derivative [Line Items]
Total debt	$ 1,638.7	$ 1,988.3
Carrying (Reported) Amount, Fair Value Disclosure
Derivative [Line Items]
Variable rate debt	843.8	1,187.5
Fixed rate debt	819.3	819.3
Total debt	1,663.1	2,006.8
Estimate of Fair Value, Fair Value Disclosure
Derivative [Line Items]
Variable rate debt	843.8	1,187.5
Fixed rate debt	814.3	824.5
Total debt	$ 1,658.1	$ 2,012.0