INCOME TAXES - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2027	Dec. 31, 2026	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Income Tax Provision [Line Items]
Income tax (expense) benefit	$ (14,424)	$ 125,434	$ (268)
Effective tax rate	25.57%	(624.39%)	(2.49%)
U.S. federal statutory rate	21.00%	21.00%	21.00%
Reduction of valuation allowance for deferred tax assets	$ (16,500)	$ (126,600)
Minimum cumulative percentage of change in ownership as condition to offset taxable income	50.00%
Other tax attributes, subject to limitation	$ 21,200
Unrecognized tax benefits resulting from prior tax positions	2,900
Additions for current year positions	4,300
Reduction for prior year positions	1,355
Unrecognized tax benefits	9,021	6,076
Foreign Net Deferred Tax Asset
Income Tax Provision [Line Items]
Reduction of valuation allowance for deferred tax assets	1,800
Flexion
Income Tax Provision [Line Items]
Reduction of valuation allowance for deferred tax assets	12,500
Capital Loss Carryforward
Income Tax Provision [Line Items]
Reduction of valuation allowance for deferred tax assets	2,200
Federal
Income Tax Provision [Line Items]
Reduction of valuation allowance for deferred tax assets		$ (126,600)
Net operating losses	662,600
Net operating loss, subject to limitation	531,700
Federal | Flexion
Income Tax Provision [Line Items]
Net operating losses	538,600
Federal | Forecast
Income Tax Provision [Line Items]
Expected additional NOLs, year one									$ 35,400
Expected additional NOLs, year two								$ 35,400
Expected additional NOLs, year three							$ 35,400
Expected additional NOLs, year four						$ 35,400
Expected additional NOLs, year five					$ 30,800
Expected additional NOLs, year six				$ 6,900
Expected additional NOLs, thereafter				$ 6,900
Federal | Research Tax Credit Carryforward
Income Tax Provision [Line Items]
Tax credit carryforward, amount	25,900
Federal | Research Tax Credit Carryforward | Flexion
Income Tax Provision [Line Items]
Tax credit carryforward, amount	11,000
State
Income Tax Provision [Line Items]
Net operating losses	171,600
State | Flexion
Income Tax Provision [Line Items]
Net operating losses	28,600
State | Research Tax Credit Carryforward
Income Tax Provision [Line Items]
Tax credit carryforward, amount	9,500
State | Research Tax Credit Carryforward | Flexion
Income Tax Provision [Line Items]
Tax credit carryforward, amount	3,600
Non-US
Income Tax Provision [Line Items]
Net operating losses	$ 10,300