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Related Party Transactions - Additional Information (Details) - USD ($) |  |  | 3 Months Ended | 4 Months Ended | 12 Months Ended |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Nov. 23, 2020 | Aug. 21, 2020 | Mar. 31, 2022 | Mar. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2021 | Dec. 31, 2020 | Sep. 30, 2021 | Nov. 27, 2020 | Sep. 30, 2020 | Aug. 31, 2020
Related Party Transaction [Line Items] |  |  |  |  |  |  |  |  |  |  |
Expenses incurred and paid |  |  | $ 3,601,000 | $ 3,193,000 |  | $ 18,113,000 | $ 4,452,000 |  |  |  |
Promissory note - related party |  |  |  |  | $ 20,293,000 |  | 20,293,000 |  |  |  |
SPRING VALLEY ACQUISITION CORP |  |  |  |  |  |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |  |  |  |  |  |
Accrued expenses |  |  | 4,946,034 |  | 49,934 | 40,000 | 49,934 |  |  |  |
Face amount |  | $ 300,000 |  |  |  |  |  |  |  |  |
Promissory note - related party |  |  |  |  | 0 | 0 | 0 | $ 0 |  | $ 0 | $ 0
Repayment of promissory note - related party |  |  |  |  | 124,826 |  |  |  |  |  |
Loan conversion agreement warrant |  |  | $ 1,500,000 |  |  |  |  |  |  |  |
Exercise price of warrants |  |  | $ 1.00 |  |  |  |  |  | $ 11.50 |  |
Working capital Loans outstanding |  |  | $ 0 |  |  | 0 |  |  |  |  |
SPRING VALLEY ACQUISITION CORP | Affiliate |  |  |  |  |  |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |  |  |  |  |  |
Administrative expenses - related party | $ 10,000 |  |  |  |  |  |  |  |  |  |
SPRING VALLEY ACQUISITION CORP | Sponsor |  |  |  |  |  |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |  |  |  |  |  |
Face amount |  | $ 300,000 |  |  |  |  |  |  |  |  |
SPRING VALLEY ACQUISITION CORP | Administrative Support Agreement |  |  |  |  |  |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |  |  |  |  |  |
Expenses incurred and paid |  |  | 30,000 | $ 30,000 | 0 | 120,000 |  |  |  |  |
Accrued expenses |  |  | $ 50,000 |  |  | 40,000 |  |  |  |  |
Outstanding balance of related party note |  |  |  |  | 0 |  | 0 |  |  |  |
Repayment of promissory note - related party |  |  |  |  |  | 0 |  |  |  |  |
SPRING VALLEY ACQUISITION CORP | Administrative Support Agreement | Affiliate |  |  |  |  |  |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |  |  |  |  |  |
Administrative expenses - related party | $ 10,000 |  |  |  |  |  |  |  |  |  |
SPRING VALLEY ACQUISITION CORP | Related Party Loans |  |  |  |  |  |  |  |  |  |  |
Related Party Transaction [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loan conversion agreement warrant |  |  |  |  |  | $ 1,500,000 |  |  |  |  |
Exercise price of warrants |  |  |  |  |  | $ 1.00 |  |  |  |  |
Working capital Loans outstanding |  |  |  |  | $ 0 | $ 0 | $ 0 |  |  | $ 0 | $ 0

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