Derivatives and Financial Instruments - Recorded Amounts and Estimated Fair Values (Detail) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Derivative [Line Items]
Total debt	$ 2,491.8	$ 2,317.3
Recorded Amount
Derivative [Line Items]
Variable rate debt	1,693.6	1,520.0
Fixed rate debt	819.3	819.3
Total debt	2,512.9	2,339.3
Fair Value
Derivative [Line Items]
Variable rate debt	1,693.6	1,520.0
Fixed rate debt	817.5	789.3
Total debt	$ 2,511.1	$ 2,309.3