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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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- Definition

The maximum amount which a potential loan could have repaid through issuance of warrants.

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The amount of working capital loan outstanding.

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Carrying value as of the balance sheet date of obligations incurred and payable, pertaining to costs that are statutory in nature, are incurred on contractual obligations, or accumulate over time and for which invoices have not yet been received or will not be rendered. Examples include taxes, interest, rent and utilities. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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Exercise price per share or per unit of warrants or rights outstanding.

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Sum of the carrying values as of the balance sheet date of the portions of long-term notes payable due within one year or the operating cycle if longer.

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Expenses recognized resulting from transactions (excluding transactions that are eliminated in consolidated or combined financial statements) with related party.

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Amount of selling, general and administrative expenses resulting from transactions, excluding transactions that are eliminated in consolidated or combined financial statements, with related party.

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The cash outflow for the payment of a long-term borrowing made from a related party where one party can exercise control or significant influence over another party; including affiliates, owners or officers and their immediate families, pension trusts, and so forth. Alternate caption: Payments for Advances from Affiliates.

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