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Share-Based Compensation Plans (Details 1) (USD $)	6 Months Ended
Share-Based Compensation Plans (Details 1) (USD $)	Jun. 30, 2012
Assumptions of Black-Scholes option pricing model
Expected dividend yield	3.60%
Risk-free interest rate	1.18%
Expected stock price volatility	44.40%
Expected life of options - in years	6 years 1 month 10 days
Weighted average per share fair value	$ 7.08

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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