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Stock Incentive Plans (Details 2) (USD $)
12 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Summary of fair value of the stock-based awards      
Expected volatility 65.90% 65.90% 58.80%
Risk free interest rate 2.90% 2.90% 3.00%
Expected dividend yield 2.50% 2.30% 2.40%
Expected term 7 years 3 months 18 days 7 years 3 months 18 days 7 years
Weighted average fair value per share $ 9.08 $ 7.20 $ 5.59