Earnings Per Share (Details) - $ / shares	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Outstanding equity awards not included in the calculation of diluted net loss per share:
Shares issued: Options exercised	938,000	273,000	1,000,000	905,000
Share decreases: Shares repurchased for tax purposes	(1,000)	(2,000)	(2,000)	(17,000)
Stock options
Outstanding equity awards not included in the calculation of diluted net loss per share:
Number of antidilutive securities excluded from computation of earnings per share	2,384,500	10,573,585	3,969,113	10,573,585
Range of exercise prices, lower limit	$ 4.75	$ 0.47	$ 4.00	$ 0.47
Range of exercise prices, upper limit	$ 7.04	$ 7.84	$ 7.04	$ 7.84
Unvested restricted stock awards
Outstanding equity awards not included in the calculation of diluted net loss per share:
Number of antidilutive securities excluded from computation of earnings per share	0	34,845	0	34,845
Shares issued: Restricted stock awards granted	50,000	30,000	333,000	30,000
Warrant
Outstanding equity awards not included in the calculation of diluted net loss per share:
Number of antidilutive securities excluded from computation of earnings per share	0	1,602,489	0	1,602,489
Warrants, exercise price	$ 0.00	$ 2.40	$ 0.00	$ 2.40
2000ESPP
Outstanding equity awards not included in the calculation of diluted net loss per share:
Shares issued: Shares purchased under stock plan	143,000	68,000	143,000	266,000