Income Taxes - Provision for Income Taxes (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Currently payable
International	[1]	$ 88.5	$ 112.2	$ 79.8
Total current taxes		88.5	112.2	79.8
Deferred
International	[1]	(92.5)	(44.8)	(9.0)
Total deferred taxes		(92.5)	(44.8)	(9.0)
Total provision (benefit) for income taxes		$ (4.0)	$ 67.4	$ 70.8

[1] “International” represents non-U.K. taxes.