NET INCOME (LOSS) PER SHARE (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Numerator:
Net income (loss)	$ (46,985)	$ (34,692)	$ (120,772)	$ 12,782
Denominator:
Weighted-average common shares outstanding	109,343	97,590	102,739	91,834
Less: unvested RSAs (in shares)	(2,418)	(2,563)	(2,418)	(2,563)
Weighted-average common shares outstanding - basic	106,925	95,027	100,321	89,271
Dilutive effect of equity incentive plans and ESPP (in shares)				2,442
Weighted-average common shares outstanding and dilutive potential common shares - diluted	106,925	95,027	100,321	91,713
Net income (loss) per share:
Basic net income (loss) per share (in dollars per share)	$ (0.44)	$ (0.37)	$ (1.20)	$ 0.14
Diluted net income (loss) per share (in dollars per share)	$ (0.44)	$ (0.37)	$ (1.20)	$ 0.14
Securities that could potentially dilute basic EPS in the future
Anti-dilutive securities (in shares)	14,093	11,766	20,423	9,583
Equity incentive plans and ESPP
Securities that could potentially dilute basic EPS in the future
Anti-dilutive securities (in shares)	3,590	5,098	4,161	2,915
Convertible subordinated notes
Securities that could potentially dilute basic EPS in the future
Anti-dilutive securities (in shares)	10,503	6,668	16,262	6,668