Cover Page - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2020	Feb. 22, 2021	Jun. 30, 2020
Document Information [Line Items]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Document Transition Report	false
Entity File Number	1-12387
Entity Registrant Name	TENNECO INC
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	76-0515284
Entity Address, Address Line One	500 North Field Drive
Entity Address, City or Town	Lake Forest
Entity Address, State or Province	IL
Entity Address, Postal Zip Code	60045
City Area Code	847
Local Phone Number	482-5000
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 0.4
Documents Incorporated by Reference	Portions of Tenneco Inc.’s Definitive Proxy Statement related to the 2021 Annual Meeting of Stockholders to be filed subsequently are incorporated by reference into Part III of this Form 10-K.
Entity Central Index Key	0001024725
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Amendment Flag	false
ICFR Auditor Attestation Flag	true
Class A
Document Information [Line Items]
Title of 12(b) Security	Class A Voting Common Stock, par value $.01 per share
Trading Symbol	TEN
Security Exchange Name	NYSE
Entity Common Stock, Shares Outstanding		66,435,872
Class B
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		15,253,363
Preferred Stock
Document Information [Line Items]
Title of 12(b) Security	Preferred Stock Purchase Rights
No Trading Symbol Flag	true
Security Exchange Name	NYSE