CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Current Assets
Allowance for doubtful accounts	$ 115.7	$ 110.8
Other Assets
Accumulated amortization on intangible assets	$ 367.7	$ 339.9
Shareholders' Equity
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, authorized (in shares)	25,000,000	25,000,000
Preferred stock, issued (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, authorized (in shares)	125,000,000	125,000,000
Common stock, issued (in shares)	116,795,899	116,303,729
Treasury stock at cost (in shares)	56,044,485	50,226,525