Significant Accounting Policies - Noncurrent Deferred Tax Assets Recorded in Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Equity [Abstract]
Balance at beginning of period	$ 49.8	$ 80.2	$ 50.1	$ 69.7
Tax effect of other comprehensive (earnings) loss	(0.4)	(0.7)	(0.7)	9.8
Balance at end of period	$ 49.4	$ 79.5	$ 49.4	$ 79.5