Stock Compensation Plans Stock Compensation Plans (TSR Award Assumptions) (Details 10) (TSR Performance Based Equity Awards Granted in 2012 [Member] [Member], USD $)	12 Months Ended
Dec. 31, 2012 Rate
TSR Performance Based Equity Awards Granted in 2012 [Member] [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant-date fair value, granted	$ 24.68
Risk-free interest rate	0.42%
Expected life	2 years 9 months 22 days
Expected volatility	45.20%
Dividend yield	0.00%

The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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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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