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Shareholders' Deficit - Common Stock Shares (Details) - $ / shares |  | 1 Months Ended | 3 Months Ended | 12 Months Ended |  |
--- | --- | --- | --- | --- | --- | ---
Aug. 31, 2020 | Sep. 30, 2020 | Mar. 31, 2022 | Dec. 31, 2020 | Dec. 31, 2021 | Mar. 31, 2021 | Dec. 31, 2019
Class of Stock [Line Items] |  |  |  |  |  |  |
Temporary equity, shares outstanding |  |  | 6,000,000 | 6,000,000 | 6,000,000 | 6,000,000 | 6,000,000
SPRING VALLEY ACQUISITION CORP | Class A Common Stock |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |
Common shares, shares authorized (in shares) | 300,000,000 | 300,000,000 | 300,000,000 | 300,000,000 | 300,000,000 |  |
Common shares, par value (in dollars per share) | $ 0.0001 | $ 0.0001 | $ 0.0001 | $ 0.0001 | $ 0.0001 |  |
Common Stock, Voting Rights | one | one | one | one | one |  |
Common shares, shares issued (in shares) | 0 | 0 | 0 | 0 | 0 |  |
Common shares, shares outstanding | 0 | 0 | 0 | 0 | 0 |  |
Temporary equity, shares outstanding |  |  | 23,000,000 |  | 23,000,000 |  |
SPRING VALLEY ACQUISITION CORP | Class A Ordinary Shares Subject to Possible Redemption. |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |
Class A common stock subject to possible redemption, issued (in shares) | 23,000,000 | 23,000,000 |  | 23,000,000 | 23,000,000 |  |
Temporary equity, shares outstanding | 23,000,000 | 23,000,000 |  | 23,000,000 | 23,000,000 |  |
SPRING VALLEY ACQUISITION CORP | Class B ordinary share |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |
Common shares, shares authorized (in shares) | 30,000,000 | 30,000,000 | 30,000,000 | 30,000,000 | 30,000,000 |  |
Common shares, par value (in dollars per share) | $ 0.0001 | $ 0.0001 | $ 0.0001 | $ 0.0001 | $ 0.0001 |  |
Common Stock, Voting Rights | one | one | one | one | one |  |
Common shares, shares issued (in shares) | 5,750,000 | 5,750,000 | 5,750,000 | 5,750,000 | 5,750,000 |  |
Common shares, shares outstanding | 5,750,000 | 5,750,000 | 5,750,000 | 5,750,000 | 5,750,000 |  |
Aggregated shares issued upon converted basis (in percent) | 20.00% | 20.00% | 20.00% | 20.00% | 20.00% |  |

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- Definition Percentage of outstanding stock after stock conversion issuable pursuant to initial business combination transaction. + References No definition available. + Details
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- Definition Face amount or stated value per share of common stock. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(29)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
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- Definition The maximum number of common shares permitted to be issued by an entity's charter and bylaws. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(29)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
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- Definition Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(29)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
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- Definition Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=123467817&loc=d3e21463-112644 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(29)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
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- Definition Description of voting rights of common stock. Includes eligibility to vote and votes per share owned. Include also, if any, unusual voting rights. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=123467817&loc=d3e21475-112644 + Details
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- Definition The number of securities classified as temporary equity that have been sold (or granted) to the entity's shareholders. Securities issued include securities outstanding and securities held in treasury. Temporary equity is a security with redemption features that are outside the control of the issuer, is not classified as an asset or liability in conformity with GAAP, and is not mandatorily redeemable. Includes any type of security that is redeemable at a fixed or determinable price or on a fixed or determinable date or dates, is redeemable at the option of the holder, or has conditions for redemption which are not solely within the control of the issuer. If convertible, the issuer does not control the actions or events necessary to issue the maximum number of shares that could be required to be delivered under the conversion option if the holder exercises the option to convert the stock to another class of equity. If the security is a warrant or a rights issue, the warrant or rights issue is considered to be temporary equity if the issuer cannot demonstrate that it would be able to deliver upon the exercise of the option by the holder in all cases. Includes stock with put option held by ESOP and stock redeemable by holder only in the event of a change in control of the issuer. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(27)(b)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
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- Definition The number of securities classified as temporary equity that have been issued and are held by the entity's shareholders. Securities outstanding equals securities issued minus securities held in treasury. Temporary equity is a security with redemption features that are outside the control of the issuer, is not classified as an asset or liability in conformity with GAAP, and is not mandatorily redeemable. Includes any type of security that is redeemable at a fixed or determinable price or on a fixed or determinable date or dates, is redeemable at the option of the holder, or has conditions for redemption which are not solely within the control of the issuer. If convertible, the issuer does not control the actions or events necessary to issue the maximum number of shares that could be required to be delivered under the conversion option if the holder exercises the option to convert the stock to another class of equity. If the security is a warrant or a rights issue, the warrant or rights issue is considered to be temporary equity if the issuer cannot demonstrate that it would be able to deliver upon the exercise of the option by the holder in all cases. Includes stock with put option held by ESOP and stock redeemable by holder only in the event of a change in control of the issuer. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(27)(b)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
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