Stock-Based Compensation - Fair Value of Options Estimated Using Black-Scholes Option Pricing Model (Details)
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]      
Risk-free interest rates 1.11% 0.69% 1.55%
Expected term 5 years 5 years 5 years
Expected dividends 0.00% 0.00% 0.00%
Expected volatility 46.80% 49.00% 52.10%