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Stockholders' Equity (Summary of Assumptions Used to Value Stock Option Grants) (Details)
12 Months Ended
Dec. 31, 2013
suboptimal_exercise_factor
Dec. 31, 2012
suboptimal_exercise_factor
Dec. 31, 2011
suboptimal_exercise_factor
Stockholders' Equity and Stock-based Compensation Disclosure [Abstract]      
Dividend yield 0.00% 0.00% 0.00%
Expected volatility, minimum 51.00% 55.00% 51.00%
Expected volatility, maximum 54.00% 65.00% 65.00%
Risk-free interest rate, minimum 1.87% 1.61% 2.05%
Risk-free interest rate, maximum 2.71% 2.01% 3.42%
Suboptimal exercise factor, minimum 2.33 2.26 2.17
Suboptimal exercise factor, maximum 3.92 3.65 3.64