CASH, CASH EQUIVALENTS AND SHORT-TERM INVESTMENTS - LEVEL 3 (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016	Sep. 09, 2014
Changes in fair value of all financial liabilities measured at fair value on a recurring basis
Earnings Per Share, Basic and Diluted	$ (0.43)	$ (0.34)
Convertible Notes
Estimated fair value of debt instruments
Interest rate (as a percent)	2.50%			2.50%
Par value of debt	$ 345,000		$ 345,000	$ 345,000
Level 2 | Convertible Notes | Fair Value
Estimated fair value of debt instruments
Estimated fair value of debt	324,000		$ 390,000
Contingent consideration | Level 3
Changes in fair value of all financial liabilities measured at fair value on a recurring basis
Balance at the beginning of the period	14,825
Balance at the end of the period	8,611
Contingent consideration | Level 3 | Interest Expense.
Changes in fair value of all financial liabilities measured at fair value on a recurring basis
Net accretion value adjustments	531
Contingent consideration | Level 3 | Selling general and administrative expense
Changes in fair value of all financial liabilities measured at fair value on a recurring basis
Net accretion value adjustments	(5,000)
Contingent consideration | Level 3 | Royalties and milestone paid
Changes in fair value of all financial liabilities measured at fair value on a recurring basis
Net accretion value adjustments	(1,745)
Contingent consideration | Level 3 | Zipsor
Changes in fair value of all financial liabilities measured at fair value on a recurring basis
Balance at the beginning of the period	1,489
Balance at the end of the period	797
Contingent consideration | Level 3 | Zipsor | Interest Expense.
Changes in fair value of all financial liabilities measured at fair value on a recurring basis
Net accretion value adjustments	32
Contingent consideration | Level 3 | Zipsor | Selling general and administrative expense
Changes in fair value of all financial liabilities measured at fair value on a recurring basis
Net accretion value adjustments	(724)
Contingent consideration | Level 3 | Lazanda
Changes in fair value of all financial liabilities measured at fair value on a recurring basis
Balance at the beginning of the period	11,742
Balance at the end of the period	7,058
Contingent consideration | Level 3 | Lazanda | Interest Expense.
Changes in fair value of all financial liabilities measured at fair value on a recurring basis
Net accretion value adjustments	438
Contingent consideration | Level 3 | Lazanda | Selling general and administrative expense
Changes in fair value of all financial liabilities measured at fair value on a recurring basis
Net accretion value adjustments	(3,377)
Contingent consideration | Level 3 | Lazanda | Royalties and milestone paid
Changes in fair value of all financial liabilities measured at fair value on a recurring basis
Net accretion value adjustments	(1,745)
Contingent consideration | Level 3 | CAMBIA
Changes in fair value of all financial liabilities measured at fair value on a recurring basis
Balance at the beginning of the period	1,594
Balance at the end of the period	756
Contingent consideration | Level 3 | CAMBIA | Interest Expense.
Changes in fair value of all financial liabilities measured at fair value on a recurring basis
Net accretion value adjustments	61
Contingent consideration | Level 3 | CAMBIA | Selling general and administrative expense
Changes in fair value of all financial liabilities measured at fair value on a recurring basis
Net accretion value adjustments	$ (899)