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Share-Based Compensation Plans (Schedule Of Weighted-Average Assumptions) (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Share-Based Compensation Plans [Abstract]
Weighted-average grant date fair value of options granted	$ 20.29	$ 17.32	$ 15.44
Risk free rate of return	1.20%	2.40%	2.80%
Expected volatility	41.40%	39.50%	38.10%
Expected term	6 years 1 month 6 days	6 years	6 years 1 month 6 days
Expected dividend yield	0.00%	0.00%	0.00%

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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