ACCUMULATED OTHER COMPREHENSIVE LOSS - Summary of Components of AOCI (Details) - USD ($) $ in Millions	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income
Total equity	$ 2,560	$ 2,688	$ 2,815	$ 3,237	$ 3,558	$ 5,944
Foreign currency translation adjustments
Accumulated Other Comprehensive Income
Total equity	(2,129)		(2,111)
Pension and postretirement benefit plan adjustments, net of tax
Accumulated Other Comprehensive Income
Total equity	(27)		(26)
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income
Total equity	$ (2,156)	$ (2,061)	$ (2,137)	$ (2,053)	$ (2,068)	$ (1,896)