Document and Entity Information - USD ($)	4 Months Ended
	Dec. 31, 2020	Mar. 30, 2021
Document Information [Line Items]
Document Type	10-K
Document Period End Date	Dec. 31, 2020
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Document Annual Report	true
Document Transition Report	false
Entity Interactive Data Current	Yes
Entity Registrant Name	SPRING VALLEY ACQUISITION CORP.
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Current Reporting Status	Yes
Entity Ex Transition Period	false
Entity Shell Company	true
Entity Public Float	$ 242,650,000
Entity Central Index Key	0001822966
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Amendment Flag	false
Units, each consisting of one share of Class A Common Stock and one-half of one Warrant
Document Information [Line Items]
Title of 12(b) Security	Units, each consisting of one Class A ordinary share, $0.0001 par value, and one-half of one redeemable warrant
Trading Symbol	SVSVU
Security Exchange Name	NASDAQ
Class A Common Stock
Document Information [Line Items]
Title of 12(b) Security	Class A ordinary shares included as part of the units
Trading Symbol	SVSV
Security Exchange Name	NASDAQ
Entity Common Stock, Shares Outstanding		23,000,000
Warrants, each whole warrant exercisable for one share of Class A Common Stock at an exercise price of $11.50
Document Information [Line Items]
Title of 12(b) Security	Warrants included as part of the units, each whole warrant exercisable for one Class A ordinary share at an exercise price of $11.50
Trading Symbol	SVSVW
Security Exchange Name	NASDAQ
Class B Common Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		5,750,000