Derivatives and Financial Instruments - Recorded Amounts and Estimated Fair Values (Detail) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Derivative [Line Items]
Total debt	$ 1,091.1	$ 894.1
Recorded Amount
Derivative [Line Items]
Variable rate debt	595.0	395.0
Fixed rate debt	507.6	507.6
Total debt	1,102.6	902.6
Fair Value
Derivative [Line Items]
Variable rate debt	595.0	395.0
Fixed rate debt	522.2	564.3
Total debt	$ 1,117.2	$ 959.3