Cover Page - USD ($)	12 Months Ended
	Dec. 31, 2021	Mar. 05, 2022	Jun. 30, 2021
Document Information [Line Items]
Document Type	10-K
Amendment Flag	false
Document Annual Report	true
Document Transition Report	false
Document Period End Date	Dec. 31, 2021
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	FY
Current Fiscal Year End Date	--12-31
Entity Registrant Name	Montauk Renewables, Inc.
Entity File Number	001-39919
Entity Incorporation, State or Country Code	DE
Entity Interactive Data Current	Yes
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity Filer Category	Accelerated Filer
Entity Tax Identification Number	85-3189583
Entity Small Business	false
Entity Emerging Growth Company	true
Entity Address, Address Line One	680 Andersen Drive
Entity Address, Address Line Two	5th Floor, Pittsburgh
Entity Address, State or Province	PA
Entity Address, City or Town	Pittsburgh
Entity Address, Postal Zip Code	15220
City Area Code	412
Local Phone Number	747-8700
Title of 12(b) Security	Common Stock, par value $0.01 per share
Trading Symbol	MNTK
Security Exchange Name	NASDAQ
ICFR Auditor Attestation Flag	false
Entity Common Stock, Shares Outstanding		143,603,681
Entity Central Index Key	0001826600
Entity Ex Transition Period	false
Entity Public Float			$ 317,682,659
Auditor Name	GRANT THORNTON LLP
Auditor Firm ID	248
Auditor Location	Pittsburgh, Pennsylvania