Consolidated Statement of Changes in Equity (Parenthetical) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash dividends declared (USD per share)		$ 4.58	$ 4.27	$ 3.99
Retained Earnings
Acquisition and surrender of common shares	[1]	$ 36.6	$ 170.5	$ 15.8

[1] For accounting purposes, the Company treats repurchased shares as constructively retired when acquired and accordingly charges the purchase price against Common Stock par value, Additional paid-in capital, to the extent available, and Retained earnings. The change in Retained earnings of $36.6 million, $170.5 million and $15.8 million in 2023, 2022 and 2021, respectively, reflects this accounting treatment.