INCOME TAXES - Narrative (Details) - USD ($)			1 Months Ended		12 Months Ended
	Jun. 09, 2023	Apr. 21, 2023	Jun. 30, 2023	Aug. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Jul. 31, 2023	Mar. 13, 2023	Aug. 15, 2022	Dec. 31, 2020	Mar. 31, 2018
Operating Loss Carryforwards [Line Items]
Valuation allowance					$ 140,104,000	$ 138,710,000
Change in valuation allowance					1,400,000
Valuation allowance, increase in deferred tax expense					7,800,000
Valuation allowance increase in Other Comprehensive Income					400,000
Valuation allowance, decrease recorded to equity					6,800,000
Capital contribution from related-party in connection with exchange transaction						29,847,000
2.50% Notes extinguished in connection with exchange transaction					0	49,624,000	$ 0
Accrued interest, related-party					0	663,000
Debt discount, deferred tax liability					7,785,000	24,000
Unrecognized tax benefits					8,844,000	13,596,000	7,556,000				$ 4,866,000
Uncertain tax positions that would impact the effective tax rate					600,000
Interest and penalties					100,000	0	0
Payments on accrued interest and penalties					100,000	0	0
R&D tax incentive					1,122,000	0		$ 1,100,000
August 2022 Exchange Transaction | Jack W. Schuler Living Trust | Embedded Warrant
Operating Loss Carryforwards [Line Items]
Warrants fair value										$ 3,800,000
August 2022 Exchange Agreement | Jack W. Schuler Living Trust | Embedded Warrant
Operating Loss Carryforwards [Line Items]
Warrants fair value				$ 3,800,000
Convertible Notes | 2.50% Convertible Notes due 2023
Operating Loss Carryforwards [Line Items]
Interest rate									2.50%			2.50%
Accrued interest, related-party	$ 1,000,000
Aggregate principal amount			$ 10,000,000									$ 150,000,000
Total convertible notes			$ 66,900,000		726,000	56,413,000
Loss (gain) on extinguishment of debt						(3,600,000)	$ (4,900,000)
Convertible Notes | 5.00% Convertible Notes Due 2026
Operating Loss Carryforwards [Line Items]
Interest rate	5.00%		5.00%
Total convertible notes			$ 66,900,000		36,102,000	0
Loss (gain) on extinguishment of debt			(14,100,000)
Embedded derivative and related debt discount			38,200,000
Embedded derivative liability, deferred tax asset			9,500,000
Debt discount, deferred tax liability			$ 9,500,000
Convertible Notes | August 2022 Exchange Transaction | 2.50% Convertible Notes due 2023 | Jack W. Schuler Living Trust
Operating Loss Carryforwards [Line Items]
Aggregate principal amount exchanged				49,900,000
Convertible Notes | Restructuring Support Agreement | 2.50% Convertible Notes due 2023
Operating Loss Carryforwards [Line Items]
Aggregate principal amount exchanged	$ 55,900,000
Accrued interest, related-party	1,000,000
Convertible Notes | Restructuring Support Agreement | 5.00% Convertible Notes Due 2026
Operating Loss Carryforwards [Line Items]
2.50% Notes extinguished in connection with exchange transaction	56,900,000
Aggregate principal amount	10,000,000
Senior Notes | 2.50% Convertible Notes due 2023 | Affiliated Entity
Operating Loss Carryforwards [Line Items]
Total convertible notes					700,000
Senior Notes | Five Point Zero Percent Secured Promissory Note | Affiliated Entity | Jack W. Schuler Living Trust
Operating Loss Carryforwards [Line Items]
2.50% Notes extinguished in connection with exchange transaction	25,400,000
Loss (gain) on extinguishment of debt	$ 6,100,000
Senior Notes | August 2022 Exchange Transaction | Five Point Zero Percent Secured Promissory Note | Affiliated Entity | Jack W. Schuler Living Trust
Operating Loss Carryforwards [Line Items]
Aggregate principal amount exchanged		$ 34,900,000		34,900,000
Total convertible notes						16,858,000
Senior Notes | August 2022 Exchange Agreement | Affiliated Entity | Jack W. Schuler Living Trust
Operating Loss Carryforwards [Line Items]
Accrued interest, related-party						700,000
Total convertible notes					0	16,900,000
Secured Debt | August 2022 Exchange Transaction | 2.50% Convertible Notes due 2023 | Jack W. Schuler Living Trust
Operating Loss Carryforwards [Line Items]
Capital contribution from related-party in connection with exchange transaction						$ 29,800,000
Secured Debt | August 2022 Exchange Agreement | 2.50% Convertible Notes due 2023 | Jack W. Schuler Living Trust
Operating Loss Carryforwards [Line Items]
Capital contribution from related-party in connection with exchange transaction					29,800,000
2.50% Notes extinguished in connection with exchange transaction				$ 49,600,000
Federal
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards					382,300,000
Operating loss carryforwards, subject to expiration					156,900,000
Operating loss carryforwards, not subject to expiration					225,400,000
Federal | R&D tax credits
Operating Loss Carryforwards [Line Items]
Tax credits					15,400,000
State
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards					373,900,000
State | R&D tax credits
Operating Loss Carryforwards [Line Items]
Tax credits					$ 13,300,000