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INCOME AND MINING TAXES - Reconciliation of Tax Provision (Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
INCOME AND MINING TAXES. |  |  |
Loss before income and mining taxes | $ (153,715) | $ (63,591) | $ (47,640)
Statutory tax rate (as a percent) | 21.00% | 21.00% | 21.00%
US Federal and State tax recovery (expense) at statutory rate | $ (32,280) | $ (13,354) | $ (10,004)
Reconciling items: |  |  |
Equity pickup in MSC | 374 | 2,626 | 2,966
Deferred foreign income inclusion | 795 | 598 | 5,963
Realized flow-through expenditures | 496 | 3,150 | 2,100
Realized flow-through premium | (338) | (2,954) | (1,675)
Tax rate changes | (147) | 976 |
Adjustment for foreign tax rates | (2,043) | (200) | 40
Other permanent differences | (7,062) | 8,540 | 4,419
Unrealized foreign exchange rate (loss)/gain | 4,663 | (1,095) | (6,935)
NOL expires and revisions | 1,066 | 810 | (120)
Valuation allowance | 33,086 | (2,941) | 476
Tax benefit | $ (1,390) | $ (3,844) | $ (2,770)

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