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Share-Based Employee Compensation Plans and Other Compensation and Benefit Plans (Black-Scholes Option Pricing Model) (Details) (Stock Option [Member])	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Stock Option [Member]
Risk-free interest rate	0.62%	1.31%
Expected life	3 years 11 months 10 days	3 years 9 months 8 days
Expected volatility	33.60%	33.30%
Expected dividend yield	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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