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Stock-Based Compensation (Details) (Stock Options [Member])	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Stock Options [Member]
Fair value assumptions
Expected dividend yield	2.10%	2.40%	2.70%
Expected volatility	43.19%	43.60%	41.79%
Expected life	7 years 4 months 24 days	6 years 6 months	6 years 6 months
Risk-free interest rate	1.41%	2.91%	2.87%

The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

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