Net Income (Loss) Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Numerator:
Continuing operations	$ 5,076	$ 10,907
Discontinued operation	(28)	(21)
Net income	$ 5,048	$ 10,886
Denominator:
Denominator for basic net income (loss) per share - weighted average shares outstanding (in shares)	52,411,000	51,358,000
Dilutive common equivalent shares:
Employee stock options and other (in shares)	2,695,000	2,449,000
Denominator for diluted net income (loss) per share-weighted average shares outstanding, assuming exercise of potential dilutive common equivalent shares (in shares)	55,106,000	53,807,000
Basic net income (loss) per share:
Continuing operations (in dollars per share)	$ 0.10	$ 0.21
Discontinued operation (in dollars per share)	$ 0.00	$ 0.00
Total operations (in dollars per share)	$ 0.10	$ 0.21
Diluted net income (loss) per share:
Continuing operations (in dollars per share)	$ 0.09	$ 0.20
Discontinued operation (in dollars per share)	$ 0.00	$ 0.00
Total operations (in dollars per share)	$ 0.09	$ 0.20
Antidilutive securities excluded from computation of earnings per share (in share)	38,000	1,100,000