CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Allowance for doubtful accounts on trade receivables	$ 9.3	$ 4.2
Accumulated depreciation on property, plant and equipment	250.5	243.1
Accumulated amortization on intangible assets	$ 39.3	$ 19.0
Treasury Stock, at cost, shares (shares)	777,181us-gaap_TreasuryStockShares	754,853us-gaap_TreasuryStockShares
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)	53,925,029	53,231,651
Treasury Stock, at cost, shares (shares)	777,181	754,853

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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A valuation allowance for trade and other receivables due to an Entity within one year (or the normal operating cycle, whichever is longer) that are expected to be uncollectible.

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Face amount or stated value per share of common stock.

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The maximum number of common shares permitted to be issued by an entity's charter and bylaws.

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Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Number of common and preferred shares that were previously issued and that were repurchased by the issuing entity and held in treasury on the financial statement date. This stock has no voting rights and receives no dividends.

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