Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Current Assets:
Allowance for doubtful accounts	$ 125.3	$ 113.5
Other Assets:
Accumulated amortization on intangible assets	$ 412.8	$ 389.4
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)	117,543,804	117,190,883
Treasury stock at cost (in shares)	59,460,085	58,517,128