DEBT (Details)			3 Months Ended	9 Months Ended
	Apr. 02, 2015 USD ($)	Sep. 09, 2014 USD ($) item $ / shares	Sep. 30, 2015 USD ($)	Sep. 30, 2015 USD ($)	Dec. 31, 2014 USD ($)
Carrying amounts of debt
Net carrying amount of the Senior Notes			$ 562,984,000	$ 562,984,000
Net carrying amount of the Convertible Notes			239,625,000	239,625,000	$ 229,891,000
Interest expense incurred
Unamortized discount and debt issuance costs			111,400,000	111,400,000
Convertible notes due 2021
Interest expense incurred
Unamortized discount and debt issuance costs			105,400,000	105,400,000
Other Assets
Interest expense incurred
Unamortized discount and debt issuance costs			6,000,000	6,000,000
Senior Secured Notes
Long-term debt
Principal amount	$ 575,000,000		575,000,000	575,000,000
Proceeds from the issuance of debt	$ 562,000,000
April 2, 2018				57,500,000
April 2, 2019				115,000,000
April 2, 2020				115,000,000
April 2, 2021				143,750,000
April 2, 2022				143,750,000
Amount that can be paid after first year but before second anniversary				100,000,000
Threshold limit to repay principal amount outstanding in full				100,000,000
Threshold limit of asset dispositions which is required to make mandatory prepayments on senior notes				10,000,000
Carrying amounts of debt
Principal amount of the Notes			575,000,000	575,000,000
Unamortized debt discount balance			(12,016,000)	(12,016,000)
Debt issuance costs			0	500,000
Net carrying amount of the Senior Notes			562,984,000	562,984,000
Interest expense incurred
Stated coupon interest			15,796,000	31,078,000
Amortization of debt discount and debt issuance costs			487,000	958,000
Total interest expense			16,283,000	32,036,000
Senior Secured Notes | Three month LIBOR
Long-term debt
Basis spread (as a percent)	9.75%
Debt instrument, floor rate (as a percent)	1.00%
Interest rate through third anniversary (as a percent)	11.95%
Interest rate after third anniversary (as a percent)	12.95%
Senior Secured Notes | NUCYNTA
Long-term debt
Proceeds from the issuance of debt	$ 550,000,000
Convertible notes due 2021
Long-term debt
Principal amount		$ 345,000,000	$ 345,000,000	$ 345,000,000	$ 345,000,000
Interest rate (as a percent)		2.50%	2.50%	2.50%
Net proceeds from debt offering		$ 334,200,000
Underwriting discount		10,400,000
Offering expenses		$ 400,000
Trading days, number | item		20
Consecutive trading days, period		30 days
Stock price trigger | $ / shares		$ 25.01
Stock price trigger (as a percent)		130.00%
Conversion price (in dollars per share) | $ / shares		$ 19.24
Business days, period		5 days
Consecutive trading-day period		5 days
Principal amount		$ 1,000
Maximum product of the closing sale price of shares of the Company's common stock and the applicable conversion rate for such trading day (as a percent)		98.00%
Trading days preceding maturity taken for conversion		2 days
Observation period		40 days
Effective interest rate (as a percent)		9.34%
Carrying amounts of debt
Principal amount of the Notes			$ 345,000,000	$ 345,000,000
Unamortized debt discount balance		$ (119,000,000)	(105,375,000)	(105,375,000)
Net carrying amount of the Convertible Notes		226,000,000	239,625,000	239,625,000
Interest expense incurred
Stated coupon interest			2,156,000	6,469,000
Amortization of debt discount and debt issuance costs			3,564,000	10,498,000
Total interest expense			$ 5,720,000	$ 16,967,000
Convertible notes due 2021 | Other Assets
Carrying amounts of debt
Debt issuance costs		7,100,000
Convertible notes due 2021 | Additional Paid-In Capital
Long-term debt
Equity issuance costs		$ 3,700,000