Consolidated Statements of Income - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Income Statement [Abstract]
Revenue from Contract with Customer, Including Assessed Tax	$ 37	$ 21	$ 71	$ 50
Net sales to related companies	1,289	849	2,258	1,862
Net trade sales	1,326	870	2,329	1,912
Cost of sales	1,208	746	2,245	1,572
Research and development expenses	6	5	12	11
Selling, general and administrative expenses	2	2	5	4
Restructuring and asset related charges - net	0	0	0	2
Sundry income (expense) - net	(18)	(22)	(33)	(40)
Interest Income, Other	0	2	1	9
Interest expense and amortization of debt discount	7	11	14	19
Income before income taxes	85	86	21	273
Provision for income taxes	20	18	5	59
Net Income Attributable to Union Carbide Corporation	$ 65	$ 68	$ 16	$ 214