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Stock-Based Compensation (Details 3) (USD $)	12 Months Ended
Stock-Based Compensation (Details 3) (USD $)	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Stock-Based Compensation
Expected dividend yield	0.00%
Stock Option
Stock-Based Compensation
Expected volatility	81500.00%	36700.00%	36100.00%
Expected dividend yield	0.00%	0.00%	0.00%
Expected term (years)	3 years	6 years 3 months	6 years 3 months
Risk-free interest rate	400.00%	2560.00%
Weighted average grant date fair value	$ 14,620.00	$ 5,930.00	$ 4,000.00

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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