Capital Stock (Fair Values Of Options Granted During The Period Estimated Using Weighted-Average Assumptions) (Details)	3 Months Ended
Mar. 31, 2012	Mar. 31, 2011
Capital Stock [Abstract]
Risk-free interest rate	1.41%	2.84%
Volatility factor	34.00%	34.00%
Quarterly dividend yield	0.40%	0.379%
Weighted-average expected life (years)	4.1	4.0

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