DISCONTINUED OPERATIONS - Carrying amounts of major classes of assets (Details) $ in Thousands	Dec. 31, 2019 USD ($)
Disposal Group, Including Discontinued Operation, Assets, Current [Abstract]
Restricted Cash	$ 3,787
Net property, plant and equipment	11,342
Disposal Group, Including Discontinued Operation, Assets, Noncurrent [Abstract]
Assets Held for Sale, non-current	15,143
Disposal Group, Including Discontinued Operation, Liabilities, Current [Abstract]
Current Liabilities Held for Sale	900
Disposal Group, Including Discontinued Operation, Liabilities, Noncurrent [Abstract]
Liabilities Held for Sale, non-current	5,414
Uranium And Lithium Operations | Discontinued Operations, Held-for-sale or Disposed of by Sale
Disposal Group, Including Discontinued Operation, Assets, Noncurrent [Abstract]
Net property, plant and equipment	11,342
Operating lease right-of-use assets	14
Restricted cash	3,787
Assets Held for Sale, non-current	15,143
Total Assets Held for Sale	15,143
Disposal Group, Including Discontinued Operation, Liabilities, Current [Abstract]
Asset retirement obligations - current	894
Operating lease liability - current	6
Current Liabilities Held for Sale	900
Disposal Group, Including Discontinued Operation, Liabilities, Noncurrent [Abstract]
Asset retirement obligations, net of current	5,406
Operating lease liability, net of current	8
Liabilities Held for Sale, non-current	5,414
Total Liabilities Held for Sale	$ 6,314