CAPITALIZED FEES PAID TO A RELATED PARTY (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Capitalized Fees paid to a Related Party
Net carrying value	$ 166,722	$ 180,545
Weighted average remaining amortization period	12 years 1 month 6 days
Amortization expense	$ 13,823	13,823	$ 13,823
Capitalized Fees paid to a Related Party, Future amortization
Estimated amortization expense for the year 2018	13,800
Estimated amortization expense for the year 2019	13,800
Estimated amortization expense for the year 2020	13,800
Estimated amortization expense for the year 2021	13,800
Estimated amortization expense for the year 2022	13,800
Estimated amortization expense thereafter	97,700
GSK
Capitalized Fees paid to a Related Party
Gross carrying value	220,000	220,000
Accumulated amortization	(53,278)	(39,455)
Net carrying value	166,722	180,545
GSK | United States
Capitalized Fees paid to a Related Party
Gross carrying value	120,000	120,000
GSK | Europe
Capitalized Fees paid to a Related Party
Gross carrying value	60,000	60,000
GSK | Japan
Capitalized Fees paid to a Related Party
Gross carrying value	$ 40,000	$ 40,000