COMMITMENTS AND CONTINGENCIES - Additional Information (Details)				1 Months Ended						3 Months Ended				6 Months Ended
	Feb. 10, 2021	Apr. 02, 2020	Jan. 01, 2017 USD ($)	May 31, 2023 USD ($)	Feb. 28, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020	Feb. 28, 2019 USD ($)	Jul. 31, 2016 USD ($) ft²	Jun. 30, 2023 USD ($) ft² extension_option	Mar. 31, 2023 USD ($)	Dec. 31, 2022 USD ($) quarter_period	Jun. 30, 2022 USD ($)	Jun. 30, 2023 USD ($) ft² extension_option	Jun. 30, 2022 USD ($)	Nov. 30, 2020 ft²	Apr. 30, 2018 ft²
Commitments And Contingencies [Line Items]
Operating lease, cost										$ 1,400,000			$ 1,800,000	$ 3,200,000	$ 3,600,000
Operating lease, payments										1,400,000			1,800,000	3,100,000	3,700,000
Loss on lease termination										$ 524,000			0	$ 524,000	0
Operating lease, remaining lease term										3 years 2 months 12 days				3 years 2 months 12 days
Contract cost incurred in research and development activities														$ 54,900,000
Supply Agreement, Patheon Inc.
Commitments And Contingencies [Line Items]
Purchase commitment, renewal term														1 year
Purchase commitment, option for non-auto renewal, prior written notice period														18 months
Minimum purchase commitment										$ 1,900,000				$ 1,900,000
Siegfried Evionnaz SA
Commitments And Contingencies [Line Items]
Purchase commitment, option to extend, prior notice period														12 months
Cost of purchased minimum quantity product										20,800,000				$ 20,800,000
STA Pharmaceutical Hong Kong Limited
Commitments And Contingencies [Line Items]
Minimum purchase commitment, initial term		4 years
Long-term minimum purchase commitment														15,300,000
WuXi STA
Commitments And Contingencies [Line Items]
Purchase commitment, option to extend, prior notice period	18 months
Minimum purchase commitment, initial term	4 years
Long-term purchase commitment, fixed price, period	12 months
Long-term purchase commitment, option to terminate, prior notice period (at least)	180 days
BioVectra Inc
Commitments And Contingencies [Line Items]
Long-term purchase commitment, termination amount payable												$ 32,500,000
Long-term purchase commitment, upfront payment termination amount											$ 17,500,000
Long-term purchase commitment, termination amount payable after upfront payment, number of quarterly periods | quarter_period												6
Long-term purchase commitment, termination amount payable after upfront payment, per quarter												$ 2,500,000
Long-term purchase commitment, termination amount payable after upfront payment												$ 15,000,000
Long-term purchase commitment, imputed interest on termination amount payable												17.00%
Long-term purchase commitment, upfront termination amount classified as cost of goods sold												$ 11,200,000
Amortization discount										$ 500,000				$ 900,000
Minimum
Commitments And Contingencies [Line Items]
Operating lease, incremental borrowing rates based on remaining lease term										6.65%				6.65%
Maximum
Commitments And Contingencies [Line Items]
Operating lease, incremental borrowing rates based on remaining lease term										6.94%				6.94%
Cambridge
Commitments And Contingencies [Line Items]
Area of property leased (in square feet) | ft²									45,362							65,167
Annual lease expense									$ 200,000
Monthly lease expense			$ 22,000
Cambridge | Letter of Credit | Other Assets
Commitments And Contingencies [Line Items]
Total security deposit in connection with lease										$ 1,700,000				$ 1,700,000
Cambridge | Office Space
Commitments And Contingencies [Line Items]
Area of property leased (in square feet) | ft²																	19,805
Monthly lease expense						$ 48,000		$ 100,000
Operating lease, free monthly rent, period							2 months
Lease period, number of extension options | extension_option										1				1
Lease extension period										5 years				5 years
Boston | Office Space
Commitments And Contingencies [Line Items]
Area of property leased (in square feet) | ft²										27,924				27,924
Monthly lease expense					$ 200,000
Operating lease, free monthly rent, period					5 months
Operating lease, annual rent escalation, percentage					2.00%
Payments to transfer rights and obligations of operating lease				$ 1,300,000
Proceeds from return of security deposit in connection with lease														$ 1,000,000
Boston | Office Space | Keryx Biopharmaceuticals, Inc.
Commitments And Contingencies [Line Items]
Sublease rental income													$ 400,000	$ 300,000	$ 900,000