Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Current assets:
Allowances for accounts receivable	$ 49.0	$ 47.0
Stockholders' equity:
Preferred stock, par value (USD per share)	$ 1.00	$ 1.00
Preferred stock, shares authorized	5,000,000us-gaap_PreferredStockSharesAuthorized	5,000,000us-gaap_PreferredStockSharesAuthorized
Preferred stock, shares issued	0us-gaap_PreferredStockSharesIssued	0us-gaap_PreferredStockSharesIssued
Preferred stock, shares outstanding	0us-gaap_PreferredStockSharesOutstanding	0us-gaap_PreferredStockSharesOutstanding
Common stock, par value (USD per share)	$ 0.001	$ 0.001
Common stock, shares authorized	125,000,000us-gaap_CommonStockSharesAuthorized	125,000,000us-gaap_CommonStockSharesAuthorized
Common stock, shares, issued	68,394,935us-gaap_CommonStockSharesIssued	67,667,468us-gaap_CommonStockSharesIssued
Common stock, shares outstanding	66,201,953us-gaap_CommonStockSharesOutstanding	65,474,486us-gaap_CommonStockSharesOutstanding
Treasury stock, shares	2,192,982us-gaap_TreasuryStockShares	2,192,982us-gaap_TreasuryStockShares

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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