XML 58 R43.htm IDEA: XBRL DOCUMENT

Summary of Significant Accounting Policies (Details 1)	12 Months Ended
Summary of Significant Accounting Policies (Details 1)	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Schedule of fair value of stock option granted
Volatility	39.70%	39.52%	38.98%
Interest Rates	1.24%	1.58%	2.16%
Dividend Yields	3.17%	3.03%	2.68%
Weighted Average Life (in years)	7 years	7 years	7 years 2 months 12 days

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.

+ References+ Details