CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Allowance for doubtful accounts on trade receivables	$ 16.1	$ 15.6
Accumulated depreciation on property, plant and equipment	444.7	425.2
Accumulated amortization on intangible assets	$ 201.0	$ 187.3
Class A Common Stock
Common Stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common Stock, authorized (in shares)	900,000,000	900,000,000
Common Stock, issued (in shares)	55,761,545	55,556,466
Treasury stock (in shares)	1,624,719	1,533,320