Earnings Per Share (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Outstanding equity awards not included in the calculation of diluted net loss per share:
Shares issued: Options exercised	273,000	27,000	905,000	31,000
Share decreases: Shares repurchased for tax purposes	(2,000)	(61,000)	(17,000)	(147,000)
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	10,573,585	7,299,887	10,573,585	8,725,951
Range of exercise prices, lower limit	$ 0.47	$ 1.26	$ 0.47	$ 1.06
Range of exercise prices, upper limit	$ 7.84	$ 16.36	$ 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	34,845	5,550	34,845	11,753
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross	30,000	30,000	0	30,000
Share decreases: Restricted stock awards canceled	0	0	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	1,602,489	1,602,489
Warrants, exercise price	$ 2.40	$ 2.40	$ 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	68,000	0	266,000	458,000