Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Numerator
Net Income	$ 1,314.2	$ 824.2	$ 793.0
Denominator
Weighted Average Common Shares - Basic	200,647,200	204,232,900	203,642,000
Dilution for Assumed Exercises of Stock Options and Nonvested Stock Awards	1,462,200	615,000.0	113,300
Weighted Average Common Shares - Assuming Dilution	202,109,400	204,847,900	203,755,300
Net Income Per Common Share
Basic	$ 6.55	$ 4.04	$ 3.89
Assuming Dilution	$ 6.50	$ 4.02	$ 3.89