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Common Stock and Stock-based Compensation (Details 7) (SARs Activity [Member])	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
SARs Activity [Member]
Fair value of SARs using Black-Scholes pricing model
Risk-free interest rate	0.89%	0.03%	0.11%
Dividend yield	0.00%	0.00%	0.00%
Volatility	50.00%	58.70%	58.00%
Expected lives (in years)	5 years	6 years 6 months	6 years 6 months

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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