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Equity-Based Compensation Plans (Details) (USD $)
3 Months Ended
Mar. 31, 2013
Mar. 31, 2012
Weighted-average fair values of the Company's stock options granted    
Weighted average fair value of options granted $ 11.46 $ 8.33
Expected volatility 76.00% 64.00%
Contractual life 7 years 7 years
Expected dividend yield 0.00% 0.00%
Maximum [Member]
   
Weighted-average fair values of the Company's stock options granted    
Risk-free interest rate 0.35% 0.95%
Expected life 5 years 4 months 24 days 5 years 4 months 24 days
Minimum [Member]
   
Weighted-average fair values of the Company's stock options granted    
Risk-free interest rate 0.31% 0.77%
Expected life 3 years 4 months 24 days 3 years 4 months 24 days