Derivatives and Financial Instruments - Recorded Amounts and Estimated Fair Values (Detail) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Derivative [Line Items]
Total debt	$ 1,752.6	$ 1,988.3
Recorded Amount
Derivative [Line Items]
Variable rate debt	953.3	1,187.5
Fixed rate debt	819.3	819.3
Total debt	1,772.6	2,006.8
Fair Value
Derivative [Line Items]
Variable rate debt	953.3	1,187.5
Fixed rate debt	796.7	824.5
Total debt	$ 1,750.0	$ 2,012.0