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Share-Based Compensation (Schedule of Weighted Average Assumptions Used in Valuing Stock Options Granted to Employees) (Details)
12 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Share-based Compensation [Abstract]      
Stock price volatility 34.00% 34.00% 31.00%
Risk-free interest rate 0.82% 1.88% 2.12%
Expected life (in years) 4 years 10 months 20 days 4 years 11 months 19 days 4 years 10 months 4 days
Dividend rate 0.00% 0.00% 0.00%
Forfeiture rate 5.90% 6.10% 7.00%