Significant Accounting Policies - Noncurrent Deferred Tax Assets Recorded in Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Equity [Abstract]
Balance at beginning of period	$ 49.4	$ 79.5	$ 50.1	$ 69.7
Tax effect of other comprehensive (earnings) loss	(0.4)	(1.6)	(1.1)	8.2
Balance at end of period	$ 49.0	$ 77.9	$ 49.0	$ 77.9