| Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified | Sep. 30, 2013 | Dec. 31, 2012 | 
|---|---|---|
| Consolidated Balance Sheets [Abstract] | ||
| Allowance for doubtful accounts receivable | $ 3,122 | $ 2,614 | 
| Common stock, par value per share | $ 0.01 | $ 0.01 | 
| Common stock, shares authorized | 190,000,000 | 190,000,000 | 
| Common stock, shares outstanding | 88,021,807 | 87,536,292 | 
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- Definition For an unclassified balance sheet, a valuation allowance for receivables due a company that are expected to be uncollectible. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition Face amount or stated value per share of common stock. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition The maximum number of common shares permitted to be issued by an entity's charter and bylaws. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Details 
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