CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Accounts receivable, allowance for credit loss	$ 12.9	$ 11.2
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, authorized (in shares)	10,000,000.0	10,000,000.0
Preferred stock, issued (in shares)	0	0
Common stock, par value (in dollars per share)	$ 1.25	$ 1.25
Common stock, authorized (in shares)	300,000,000.0	300,000,000.0
Common stock, issued (in shares)	189,300,000	189,300,000
Common stock, outstanding (in shares)	121,800,000	121,200,000
Treasury stock (in shares)	66,900,000	67,500,000
Stock held by employee benefit trusts (in shares)	600,000	600,000