INCOME TAXES - Deferred Taxes (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Deferred tax assets
Net operating loss carryforwards	$ 64,813	$ 121,839
Research and development tax credit carryforwards	53,467	55,211
Other	743	1,100
Total deferred tax assets before valuation allowance	119,023	178,150
Valuation allowance	(64,744)	(63,423)
Total deferred tax assets	54,279	114,727
Deferred tax liabilities
Debt issuance discount and other	(9,158)	(10,596)
Unrealized Gain on Investment, net	(27,794)	(10,372)
Net deferred tax assets	$ 17,327	$ 93,759