Net Income (Loss) Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Numerator:
Continuing operations	$ 12,655	$ (4,155)	$ 23,562	$ 7,902
Discontinued operation	(16)	110	(37)	88
Net income (loss)	$ 12,639	$ (4,045)	$ 23,525	$ 7,990
Denominator:
Denominator for basic net income (loss) per share-weighted average shares outstanding	51,456,000	51,639,000	51,314,000	51,101,000
Dilutive common equivalent shares:
Employee stock options and other	2,084,000		2,172,000	1,142,000
Denominator for diluted net income (loss) per share-weighted average shares outstanding, assuming exercise of potential dilutive common equivalent shares	53,540,000	51,639,000	53,486,000	52,243,000
Basic net income (loss) per share:
Continuing operations (in dollars per share)	$ 0.25	$ (0.08)	$ 0.46	$ 0.15
Discontinued operation (in dollars per share)	$ 0.00	$ 0.00	$ 0.00	$ 0.00
Total operations (in dollars per share)	$ 0.25	$ (0.08)	$ 0.46	$ 0.16
Diluted net income (loss) per share:
Continuing operations (in dollars per share)	$ 0.24	$ (0.08)	$ 0.44	$ 0.15
Discontinued operation (in dollars per share)	$ 0.00	$ 0.00	$ 0.00	$ 0.00
Total operations (in dollars per share)	$ 0.24	$ (0.08)	$ 0.44	$ 0.15
Antidilutive securities excluded from computation of earnings per share	1,500,000	7,800,000	1,300,000	4,600,000