Derivatives and Financial Instruments - Recorded Amounts and Estimated Fair Values (Detail) - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025
Derivative [Line Items]
Total debt	$ 1,944.3	$ 1,638.6
Recorded Amount
Derivative [Line Items]
Variable rate debt	1,157.6	852.7
Fixed rate debt	800.0	800.0
Total debt	1,957.6	1,652.7
Fair Value
Derivative [Line Items]
Variable rate debt	1,157.6	852.7
Fixed rate debt	814.9	828.2
Total debt	$ 1,972.5	$ 1,680.9