Significant Accounting Policies (Schedule Of Employee Stock Options On Estimated Weighted Average Assumptions) (Details)	12 Months Ended
Dec. 31, 2011 Y	Dec. 31, 2010 Y	Dec. 31, 2009 Y
Significant Accounting Policies [Abstract]
Divided yield	2.23%	2.20%	2.31%
Expected volatility	31.59%	31.92%	39.37%
Risk-free interest rate	2.01%	1.56%	2.43%
Expected life, years	4	4	4
Forfeiture rate	0.56%	0.56%	0.56%
Suboptimal factor	1.75	1.75	1.75

The period of time an equity-based award is expected to be outstanding. An equity-based award's expected term is generally determined based on, among other factors, the instrument's contractual term and the effects of employees' expected exercise and post-vesting employment termination behavior.

+ References+ Details

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