RESTRUCTURING AND OTHER COSTS - RESTRUCTURING ACCURALS (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Restructuring Reserve [Roll Forward]
Restructuring and other costs	$ 3	$ 43
2021 Plans
Restructuring Reserve [Roll Forward]
Beginning Balance	34
Restructuring and other costs	4
Amounts applied	(16)
Change in estimates	(1)
Ending Balance	21
Severance
Restructuring Reserve [Roll Forward]
Beginning Balance	29
Restructuring and other costs	3
Amounts applied	(14)
Change in estimates	(1)
Ending Balance	17
Severance | 2019 and Prior Plans
Restructuring Reserve [Roll Forward]
Beginning Balance	12
Restructuring and other costs	1
Amounts applied	(7)
Change in estimates	0
Ending Balance	6
Severance | 2020 Plans
Restructuring Reserve [Roll Forward]
Beginning Balance	17
Restructuring and other costs	0
Amounts applied	(7)
Change in estimates	(1)
Ending Balance	9
Severance | 2021 Plans
Restructuring Reserve [Roll Forward]
Beginning Balance	0
Restructuring and other costs	2
Amounts applied	0
Change in estimates	0
Ending Balance	2
Other Restructuring Costs
Restructuring Reserve [Roll Forward]
Beginning Balance	5
Restructuring and other costs	1
Amounts applied	(2)
Ending Balance	4
Other Restructuring Costs | 2019 and Prior Plans
Restructuring Reserve [Roll Forward]
Beginning Balance	3
Restructuring and other costs	1
Amounts applied	(1)
Ending Balance	3
Other Restructuring Costs | 2020 Plans
Restructuring Reserve [Roll Forward]
Beginning Balance	2
Restructuring and other costs	0
Amounts applied	(1)
Ending Balance	1
Other Restructuring Costs | 2021 Plans
Restructuring Reserve [Roll Forward]
Beginning Balance	0
Restructuring and other costs	0
Amounts applied	0
Ending Balance	$ 0