CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Allowance for doubtful accounts on trade receivables	$ 9.9	$ 9.3
Accumulated depreciation on property, plant and equipment	263.6	250.5
Accumulated amortization on intangible assets	$ 49.1	$ 39.3
Class A Common Stock
Common Stock, par value (usd per share)	$ 0.01	$ 0.01
Common Stock, shares authorized (shares)	900,000,000	900,000,000
Common Stock, shares issued (shares)	54,000,580	53,925,029
Treasury Stock, at cost, shares (shares)	834,612	777,181