Income Taxes - Provision for Income Taxes (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Currently payable
Federal	[1]	$ 0.0	$ (0.1)	$ 0.0
International	[2]	64.2	62.3	76.7
Total current taxes		64.2	62.2	76.7
Deferred
International	[2]	(18.4)	(4.1)	(18.0)
Total deferred taxes		(18.4)	(4.1)	(18.0)
Total provision (benefit) for income taxes		$ 45.8	$ 58.1	$ 58.7

[1] ⁽¹⁾  “Federal” represents U.K. taxes.

[2] ⁽²⁾  “International” represents non-U.K. taxes.