INCOME TAXES - Operating Loss Carryforwards and Research Tax Credits (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Operating Loss Carryforwards [Line Items]
Research tax credits	$ 18,076	$ 17,787
Federal
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards	477,839	448,250
Research tax credits	12,985	12,535
Foreign
Operating Loss Carryforwards [Line Items]
Net operating loss carry forwards	0	133
Texas
Operating Loss Carryforwards [Line Items]
Research tax credits	$ 5,091	$ 5,252