BEIGENE AGREEMENT - Narrative (Details) - Collaboration and License Agreement - USD ($)		12 Months Ended
	Jan. 07, 2018	Dec. 31, 2018
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Up-front fee received	$ 10,000,000
Termination of contract, period after first commercial sale of product	10 years
Period required for notice of termination of contract	60 days
Payments received in advance		$ 533,000
Revenue from performance obligations satisfied during reporting period		52,000
Revenue from performance obligation expected to be earned	$ 123,000,000
Licenses of Intellectual Property
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue from performance obligation earned		9,500,000
Manufacturing Supply Services
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Payments received in advance		(500,000)
Revenue from performance obligations satisfied during reporting period		100,000
Revenue from performance obligation earned		400,000
Cost-sharing receivable		300,000
Milestone Payments
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue from performance obligation earned		3,000,000
Revenue from performance obligation expected to be earned		5,000,000
Royalties
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue		$ 0