ACCUMULATED OTHER COMPREHENSIVE LOSS (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	$ 16	$ 12
Accumulated Other Comprehensive Income (Loss) [Line Items]
Union Carbide Corporation's stockholder's equity	1,438	1,815	$ 1,368	$ 1,798
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax		1
Other Comprehensive Income (Loss), Net of Tax	16	13
AOCI Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Union Carbide Corporation's stockholder's equity	(1,336)	(1,307)	(1,352)	(1,320)
Other Comprehensive Income (Loss), Net of Tax	16	13
Cumulative translation adjustments
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0	0
Accumulated Other Comprehensive Income (Loss) [Line Items]
Union Carbide Corporation's stockholder's equity	(59)	(61)	(59)	(62)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax		1
Other Comprehensive Income (Loss), Net of Tax	0	1
Pension and other postretirement benefits
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	16	12
Accumulated Other Comprehensive Income (Loss) [Line Items]
Union Carbide Corporation's stockholder's equity	(1,277)	(1,246)	$ (1,293)	$ (1,258)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax		0
Other Comprehensive Income (Loss), Net of Tax	16	12
Other Comprehensive Income (Loss), Tax	6	8
Reclassification out of Accumulated Other Comprehensive Income [Member] | Pension and other postretirement benefits
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	22	20
Reclassification from AOCI, Current Period, Tax	(6)	(8)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	$ 16	$ 12