Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Numerator
Net Income	$ 1,779.1	$ 1,283.8	$ 1,407.2
Denominator
Weighted Average Common Shares - Basic	187,497,700	196,659,700	200,647,200
Dilution for Assumed Exercises of Stock Options and Nonvested Stock Awards	571,500	942,300	1,462,200
Weighted Average Common Shares - Assuming Dilution	188,069,200	197,602,000	202,109,400
Net Income Per Common Share
Basic	$ 9.49	$ 6.53	$ 7.01
Assuming Dilution	$ 9.46	$ 6.50	$ 6.96