Net Income (Loss) Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Numerator:
Continuing operations	$ 9,833	$ 7,687	$ 17,735	$ 22,201
Discontinued operation	(20)	11	68	233
Net income	$ 9,813	$ 7,698	$ 17,803	$ 22,434
Denominator:
Denominator for basic net income (loss) per share-weighted average shares outstanding (in shares)	51,576,000	50,401,000	51,241,000	50,722,000
Dilutive common equivalent shares:
Employee stock options and other (in shares)	2,361,000	1,847,000	2,088,000	2,042,000
Denominator for diluted net income (loss) per share-weighted average shares outstanding, assuming exercise of potential dilutive common equivalent shares (in shares)	53,937,000	52,248,000	53,329,000	52,764,000
Basic net income (loss) per share:
Continuing operations (in dollars per share)	$ 0.19	$ 0.15	$ 0.35	$ 0.44
Discontinued operation (in dollars per share)	$ 0.00	$ 0.00	$ 0.00	$ 0.00
Total operations (in dollars per share)	$ 0.19	$ 0.15	$ 0.35	$ 0.44
Diluted net income (loss) per share:
Continuing operations (in dollars per share)	$ 0.18	$ 0.15	$ 0.33	$ 0.42
Discontinued operation (in dollars per share)	$ 0.00	$ 0.00	$ 0.00	$ 0.00
Total operations (in dollars per share)	$ 0.18	$ 0.15	$ 0.33	$ 0.43
Antidilutive securities excluded from computation of earnings per share (in shares)	1,300,000	3,900,000	2,400,000	2,500,000