Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
CURRENT ASSETS:
Allowance for doubtful accounts	$ 112.5	$ 110.8
OTHER ASSETS:
Accumulated amortization on intangible assets	$ 353.5	$ 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)	116,778,224	116,303,729
Treasury stock at cost (in shares)	51,433,302	50,226,525