Consolidated Statement of Changes in Equity (Parenthetical) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Common stock, dividends declared (USD per share)		$ 3.99	$ 3.71	$ 3.43
Retained Earnings
Acquisition and surrender of common shares	[1]	$ 15.8	$ 34.1	$ 28.9

[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 $15.8 million, $34.1 million and $28.9 million in 2021, 2020 and 2019, respectively, reflects this accounting treatment.