Income Taxes - Component of Income Taxes Expenses (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Currently payable:
U.S. federal and state	$ 13.3	$ 4.3	$ 34.1
Non-U.S.	14.9	22.0	51.1
Total	28.2	26.3	85.2
Deferred income taxes (benefit):
U.S. federal and state	(10.3)	(4.1)	(145.5)
Non-U.S.	(2.0)	4.3	29.6
Total	(12.3)	0.2	(115.9)
Income tax expense (benefit)	$ 15.9	$ 26.5	$ (30.7)