Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Allowance for doubtful accounts receivable	$ 16.9	$ 16.8
Accumulated amortization of finite-lived intangible assets	$ 2,802.4	$ 2,655.6
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	5,000,000.0	5,000,000.0
Preferred stock, shares issued	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	400,000,000.0	400,000,000.0
Common stock, shares issued	264,700,000	263,900,000
Common stock, shares outstanding	255,700,000	257,600,000
Treasury stock, shares	9,000,000.0	6,300,000
Class A Non-Voting Common Stock [Member]
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	5,000,000.0	5,000,000.0
Common stock, shares issued	0	0