Significant Accounting Policies (Details 6)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Employee Stock Options [Member]
Weighted-average assumptions
Risk-free interest rate (in hundredths)	1.60%	1.00%
Dividend yield (in hundredths)	0.00%	0.00%
Volatility (in hundredths)	50.50%	51.50%
Expected life	4 years 7 months 6 days	5 years 1 month 6 days
ESPP [Member]
Weighted-average assumptions
Risk-free interest rate (in hundredths)	0.10%	0.10%
Dividend yield (in hundredths)	0.00%	0.00%
Volatility (in hundredths)	59.00%	61.40%
Expected life	6 months	6 months
Board of Director Stock Options [Member]
Weighted-average assumptions
Risk-free interest rate (in hundredths)	2.30%
Dividend yield (in hundredths)	0.00%
Volatility (in hundredths)	53.30%
Expected life	7 months 3 days