Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income attributable to Union Carbide Corporation	$ 427	$ 627	$ 1,055
Other comprehensive income (loss), net of tax
Cumulative translation adjustments	1	1	2
Pension and other postretirement benefit plans	(106)	(105)	43
Net other comprehensive income	(105)	(104)	45
Comprehensive income attributable to Union Carbide Corporation	$ 322	$ 523	$ 1,100