LONG TERM DEBT (Details) (USD $)	6 Months Ended	0 Months Ended	3 Months Ended	6 Months Ended		6 Months Ended			3 Months Ended	6 Months Ended				0 Months Ended
	Jun. 30, 2013	May 29, 2013 Convertible Senior Notes Due 2020	Jun. 30, 2013 Convertible Senior Notes Due 2020	Jun. 30, 2013 Convertible Senior Notes Due 2020	May 21, 2013 Convertible Senior Notes Due 2020	Jun. 30, 2013 Convertible Senior Notes Due 2020 Additional Paid-in Capital	Jun. 30, 2013 Convertible Senior Notes Due 2020 Non-current assets	Jun. 30, 2013 Senior Secured Notes Due 2018	Jun. 30, 2013 Senior Secured Notes Due 2018 Purchase of a debt-like instrument from BioPharma	Jun. 30, 2013 Senior Secured Notes Due 2018 Purchase of a debt-like instrument from BioPharma	Mar. 25, 2013 Senior Secured Notes Due 2018 Purchase of a debt-like instrument from BioPharma	Mar. 25, 2013 Senior Secured Notes Due 2018 Purchase of a debt-like instrument from BioPharma Minimum	Mar. 25, 2013 Senior Secured Notes Due 2018 Purchase of a debt-like instrument from BioPharma Maximum	Apr. 09, 2013 Senior Secured Notes Due 2018 Purchase of a debt-like instrument from BioPharma Initial closing	Mar. 25, 2013 Senior Secured Notes Due 2018 Purchase of a debt-like instrument from BioPharma Secondary closing
Long-term debt
Amount of offering					$ 220,000,000
Additional aggregate principal amount		30,000,000
Net proceeds from offering	290,247,000	241,800,000												48,400,000
Shares of common stock into which debt is convertible				16,826,000
Conversion rate in proportion to principal amount of Convertible Notes				$ 0.0673038
Conversion price per share (in dollars per share)			$ 14.858	$ 14.858
Initial fair value of the liability component	204,738,000		154,738,000	154,738,000	154,700,000
Carrying value of the equity component					95,300,000
Debt issuance costs				8,200,000		3,100,000	5,100,000	1,600,000
Combined effective interest rate (as a percent)				15.20%
Total interest expense recognized			2,500,000	2,500,000
Amortization of debt discount			1,500,000	1,500,000
Remaining expected life				5 years 4 months 24 days
Cap price of capped call transactions (in dollars per share)				$ 20
Fair value of capped calls				34,700,000
Amount received														50,000,000
Amount received in funding and facility payments														500,000
Additional discretionary amount receivable															60,000,000
Additional discretionary amount receivable in funding and facility payments															600,000
Amount of reasonable and documented out-of-pocket legal costs and fees for which entity is responsible													300,000
Scheduled quarterly payment amount as a percentage of net sales												25.00%
Amount due as a percentage of net sales, if scheduled quarterly payments are less than 25% of the net sales											25.00%
Make-whole premium ratio											1.03
Annual implied effective interest rate (as a percent)									13.38%	13.38%
Imputed interest									$ 1,500,000	$ 1,500,000