Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2018	Feb. 11, 2019
Document and Entity Information [Abstract]
Entity Registrant Name	UNION CARBIDE CORP /NEW/
Entity Central Index Key	0000100790
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding		935.51
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float	$ 0