CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020
Statement of Financial Position [Abstract]
Accounts receivable, allowances for credit losses	$ 11.3	$ 15.9	$ 18.5
Common stock, par value (USD per share)	$ 1.00	$ 1.00	$ 1.00
Common stock authorized (in shares)	1,000,000,000	1,000,000,000	1,000,000,000
Common stock issued (in shares)	441,400,000	441,400,000	441,400,000
Treasury stock (in shares)	91,000,000	93,200,000	93,300,000