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Commitments and Contingencies (Details) - UAMPS - Development Cost Reimbursement Agreement - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Maximum reimbursement based on the current stage of project development	$ 57,000	$ 57,000
Net development costs incurred	$ 10,077	$ 5,204

X

- Definition

Represents maximum reimbursement based on the current stage of project development.

+ References

No definition available.

+ Details

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X

- Definition

Represents net development costs incurred.

+ References

No definition available.

+ Details

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Namespace Prefix:	svsvu_
Data Type:	xbrli:monetaryItemType
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Period Type:	instant

X

- Definition

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.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
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Period Type:	duration

X

- Details

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Namespace Prefix:
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X

- Details

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