INCOME TAXES (Schedule of Domestic and Foreign Components of Income Before Income Taxes and Tax Reconciliation) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Geographic Allocation of Income and Provision (Credit) for Income Taxes [Abstract]
Income (Loss) Before Income Taxes, Domestic	$ 558	$ 696	$ 1,305
Income (Loss) Before Income Taxes, Foreign	(1)	(5)	(3)
Income before income taxes	557	691	1,302
Current Federal Tax Expense (Benefit)	82	70	166
Current State and Local Tax Expense (Benefit)	2	4	6
Current Foreign Tax Expense (Benefit)	0	0	40
Current Income Tax Expense (Benefit)	84	74	212
Deferred Federal Income Tax Expense (Benefit)	42	(9)	27
Deferred State and Local Income Tax Expense (Benefit)	4	(1)	8
Deferred Income Tax Expense (Benefit)	46	(10)	35
Provision for income taxes	130	64	247
Net Income Attributable to Union Carbide Corporation	$ 427	$ 627	$ 1,055