BASIS OF PRESENTATION AND ACCOUNTING POLICIES (Details 4) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Basic and diluted net income (loss) per common share
Net income (loss), basic	$ 22,829	$ (33,895)	$ 71,090	$ (12,565)
Effect of dilutive securities:
Net income (loss), diluted	24,805	(33,895)	77,013	(12,565)
Shares used in calculating basic net income (loss) per common share	75,834,443	67,841,665	75,400,064	66,122,521
Effect of dilutive securities:
Options to purchase shares of common stock and RSUs	2,318,634	0	2,658,833	0
Shares used in calculating diluted net income (loss) per common share	85,995,727	67,841,665	85,901,660	66,122,521
Basic net income (loss) per common share (in dollars per share)	$ 0.30	$ (0.50)	$ 0.94	$ (0.19)
Diluted net income (loss) per common share (in dollars per share)	$ 0.29	$ (0.50)	$ 0.90	$ (0.19)
2017 Notes convertible into shares of common stock
Debt instrument interest rate
Notes stated interest rate percentage	2.50%		2.50%
Effect of dilutive securities:
Interest on 2017 Notes, net of tax	772	0	2,343	0
Debt issuance costs related to 2017 Notes, net of tax	104	0	315	0
Debt discount amortization related to 2017 Notes, net of tax	$ 1,100	$ 0	$ 3,265	$ 0
Effect of dilutive securities:
2017 Notes convertible into shares of common stock	7,842,650	0	7,842,763	0
2018 Notes convertible into shares of common stock
Debt instrument interest rate
Notes stated interest rate percentage	1.125%		1.125%
2020 Notes convertible into shares of common stock
Debt instrument interest rate
Notes stated interest rate percentage	1.875%		1.875%