LIABILITY RELATED TO SALE OF FUTURE ROYALTIES (Details) (USD $)	3 Months Ended	6 Months Ended				3 Months Ended	6 Months Ended	0 Months Ended
	Jun. 30, 2014	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2014 Collaborative partners	Dec. 31, 2013 Collaborative partners	Jun. 30, 2014 Liability related to sale of future royalties	Jun. 30, 2014 Liability related to sale of future royalties	Oct. 18, 2013 Liability related to sale of future royalties PDL BioPharma
Future royalties liability
Royalty and milestone payments received								$ 240,500,000
Effective annual interest rate (as a percent)							10.00%
Non-cash royalty revenue recognized	33,297,000	76,081,000				33,300,000	76,100,000
Non-cash interest expense recognized	4,903,000	10,282,000				4,900,000	10,300,000
Liability related to PDL Transaction						194,900,000	194,900,000
Amounts receivable included in Receivables from collaborative partners	$ 35,635,000	$ 35,635,000	$ 10,824,000	$ 33,200,000	$ 6,900,000