Net Income (Loss) Per Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Numerators and denominators of the basic and diluted net income (loss) per share computations
Net income (loss) (numerator)	$ 8,779	$ (4,335)	$ (24,139)
Shares calculation (denominator):
Weighted average shares outstanding- basic	115,175	101,487	95,833
Effect of dilutive securities:
Potential common stock relating to stock options, restricted stock units and ESPP	1,252
Future issued common stock related to acquisitions	0
Weighted average shares outstanding-diluted	116,427	101,487	95,833
Net income per share-basic	$ 0.08	$ (0.04)	$ (0.25)
Net income per share-diluted	$ 0.08	$ (0.04)	$ (0.25)