Stockholders' Equity (Details 5) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Assumption for fair value of the option granted
Weighted average fair value per share of stock options granted	$ 7.55	$ 8.50	$ 3.96
Stock options and restricted stock units
Assumption for fair value of the option granted
Expected dividend yield (as a percent)	0.00%	0.00%	0.00%
Risk-free interest rate, minimum (as a percent)	1.04%	0.79%	1.25%
Risk-free interest rate, maximum (as a percent)	1.86%	1.16%	2.60%
Expected volatility, minimum (as a percent)	56.34%	58.09%	59.74%
Expected volatility, maximum (as a percent)	56.84%	59.92%	60.88%
Stock options and restricted stock units | Minimum
Assumption for fair value of the option granted
Expected term	5 years 8 months 12 days	5 years 6 months	5 years 6 months
Stock options and restricted stock units | Maximum
Assumption for fair value of the option granted
Expected term	6 years 1 month 6 days	6 years 1 month 6 days	6 years 2 months 12 days
Stock Options | Minimum
Assumption for fair value of the option granted
Term of U.S. Treasury yield used in determining risk-free rate	5 years
Stock Options | Maximum
Assumption for fair value of the option granted
Term of U.S. Treasury yield used in determining risk-free rate	7 years