Consolidated Statements of Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Income Statement [Abstract]
Revenue from Contract with Customer, Including Assessed Tax	$ 31	$ 25	$ 102	$ 75
Net sales to related companies	1,244	817	3,502	2,679
Net trade sales	1,275	842	3,604	2,754
Cost of sales	1,093	787	3,338	2,359
Research and development expenses	7	6	19	17
Selling, general and administrative expenses	2	2	7	6
Restructuring and asset related charges - net	1	13	1	15
Sundry income (expense) - net	(10)	45	(43)	5
Interest Income, Other	1	1	2	10
Interest expense and amortization of debt discount	5	7	19	26
Income before income taxes	158	73	179	346
Provision for income taxes	54	14	59	73
Net Income Attributable to Union Carbide Corporation	$ 104	$ 59	$ 120	$ 273