Share-Based Compensation Plans - Outstanding Restricted Stock Unit Awards (Detail) - Restricted Stock Unit Awards - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
NUMBER
Balance at beginning of period (in shares)	2,243,183
Granted (in shares)	1,166,376
Distributed (in shares)	(847,281)
Forfeited (in shares)	(62,220)
Balance at end of period (in shares)	2,500,058
Units Convertible, at the end of year (in shares)	18,887
AGGREGATE INTRINSIC VALUE
AGGREGATE INTRINSIC VALUE	$ 211.0	$ 198.5
Units Convertible, at the end of year	$ 1.6