Earnings Per Share (Details) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Outstanding equity awards not included in the calculation of diluted net loss per share:
Shares issued: Options exercised	632,000	4,000
Share decreases: Shares repurchased for tax purposes	15,000	87,000
Stock options
Outstanding equity awards not included in the calculation of diluted net loss per share:
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	10,923,538	9,159,312
Range of exercise prices, lower limit	$ 0.47	$ 0.47
Range of exercise prices, upper limit	$ 7.84	$ 16.36
Unvested restricted stock awards
Outstanding equity awards not included in the calculation of diluted net loss per share:
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	43,220	508,221
Share decreases: Restricted stock awards canceled	0	23,000
Warrant
Outstanding equity awards not included in the calculation of diluted net loss per share:
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	1,602,489	1,602,489
Warrants, exercise price	$ 2.40	$ 2.40
2000ESPP
Outstanding equity awards not included in the calculation of diluted net loss per share:
Shares issued: Shares purchased under stock plan	198,000	458,000