CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Assets
Allowance for doubtful accounts	$ 12.2	$ 9.7
Stockholders' equity
Common stock, shares authorized (shares)	400,000,000.0	400,000,000.0
Common stock, shares issued (shares)	261,900,000	261,300,000
Treasury shares (shares)	15,200,000	14,200,000