Reconciliation of Beginning and Ending Amounts of Unrecognized Tax Benefits (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Balance at beginning of the year	$ 27.8	$ 26.0	$ 24.5
Additions for tax positions related to the current year	7.7	7.4	6.1
Additions for tax positions related to prior years	2.6	1.8	0.8
Reductions for tax positions related to prior years	(1.6)	(1.6)
Lapse of statute of limitations	(5.3)	(5.8)	(5.4)
Balance at the end of the year	$ 31.2	$ 27.8	$ 26.0