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%

Percentage of outstanding stock after stock conversion issuable pursuant to initial business combination transaction.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Face amount or stated value per share of common stock.

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-Publisher FASB
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The maximum number of common shares permitted to be issued by an entity's charter and bylaws.

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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.

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Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation.

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Description of voting rights of common stock. Includes eligibility to vote and votes per share owned. Include also, if any, unusual voting rights.

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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.

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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.

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