Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Allowance for doubtful accounts receivable	$ 16.4	$ 13.2
Accumulated amortization of finite-lived intangible assets	$ 2,315.6	$ 2,022.0
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	260,700,000	257,600,000
Common stock, shares outstanding	257,700,000	254,600,000
Treasury stock, shares	3,000,000.0	2,900,000
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