Consolidated Statements of Income - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Income Statement [Abstract]
Revenue from Contract with Customer, Including Assessed Tax	$ 34	$ 29
Net sales to related companies	969	1,013
Net trade sales	1,003	1,042
Cost of sales	1,037	826
Research and development expenses	6	6
Selling, general and administrative expenses	3	2
Restructuring and asset related charges - net	0	2
Sundry income (expense) - net	(15)	(18)
Interest Income, Other	1	7
Interest expense and amortization of debt discount	7	8
Income before income taxes	(64)	187
Provision for income taxes	(15)	41
Net Income Attributable to Union Carbide Corporation	$ (49)	$ 146