Accounting Policies - Basic and Diluted Earnings from Continuing Operations Per Common Share (Detail) - shares shares in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Earnings Per Share [Abstract]
Basic weighted-average common shares outstanding	61.4	61.9	62.3
Effect of dilutive employee and director awards	0.2	0.2	0.2
Diluted weighted-average common shares outstanding	61.6	62.1	62.5