Stock-Based Compensation (Weighted-Average Assumptions For Option Awards Granted) (Details) (Employee Stock Options [Member])	3 Months Ended
Mar. 31, 2012 Y	Mar. 31, 2011 Y
Employee Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility	36.00%	34.00%
Expected term (in years)	5.7	5.7
Risk-free interest rate	1.00%	2.10%
Expected dividend yield

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.

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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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