Derivatives and Financial Instruments - Recorded Amounts and Estimated Fair Values of Long-term Debt and Derivative Financial Instruments (Detail) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Derivative [Line Items]
Total debt	$ 1,988.3	$ 2,317.3
Carrying (Reported) Amount, Fair Value Disclosure
Derivative [Line Items]
Variable rate debt	1,187.5	1,520.0
Fixed rate debt	819.3	819.3
Total debt	2,006.8	2,339.3
Estimate of Fair Value, Fair Value Disclosure
Derivative [Line Items]
Variable rate debt	1,187.5	1,520.0
Fixed rate debt	824.5	789.3
Total debt	$ 2,012.0	$ 2,309.3