RETIREMENT AND POSTRETIREMENT BENEFIT PLANS - OBLIGATIONS AND FUNDED STATUS (Details) - USD ($) $ in Millions			12 Months Ended
	Jun. 30, 2020	Aug. 08, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Amounts recognized in the consolidated balance sheet:
Deferred credits and other liabilities — pension and postretirement obligations			$ (1,763)	$ (1,823)
Pension Benefits
Amounts recognized in the consolidated balance sheet:
Long-term receivables and other assets, net			167	149
Accrued liabilities			(9)	(96)
Deferred credits and other liabilities — pension and postretirement obligations			(578)	(720)
Total amount recognized in consolidated balance sheet			(420)	(667)
Accumulated other comprehensive loss included the following after-tax balances:
Net loss			(3)	(20)
Prior service cost			0	0
AOCI after-tax balances			(3)	(20)
Changes in the benefit obligation:
Benefit obligation — beginning of year			2,508	499
Service cost — benefits earned during the period			37	47	$ 5
Interest cost on projected benefit obligation			52	40	15
Actuarial (gain) loss			251	(41)
Curtailment (gain) loss	$ (124)		(278)	(136)
Special termination benefits			23	49
Benefits paid			(948)	(99)
Sale of Colombia assets			(24)	0
Additions due to the Acquisition		$ 193	0	2,136
Other	$ (278)		(8)	13
Benefit obligation — end of year			1,613	2,508	499
Changes in plan assets:
Fair value of plan assets — beginning of year			1,841	539
Actual return on plan assets			161	110
Employer contributions			146	41
Benefits paid			(948)	(99)
Additions due to the Acquisition			0	1,233
Other			(7)	17
Fair value of plan assets — end of year			1,193	1,841	539
Unfunded status:			(420)	(667)
Accumulated Benefit Obligation in Excess of Plan Assets
Projected benefit obligation			1,226	2,191
Accumulated benefit obligation			1,221	1,931
Fair value of plan assets			670	1,375
Plan Assets in Excess of Accumulated Benefit Obligation
Projected benefit obligation			387	317
Accumulated benefit obligation			379	311
Fair value of plan assets			523	466
Postretirement Benefits
Amounts recognized in the consolidated balance sheet:
Long-term receivables and other assets, net			0	0
Accrued liabilities			(74)	(72)
Deferred credits and other liabilities — pension and postretirement obligations			(1,185)	(1,103)
Total amount recognized in consolidated balance sheet			(1,259)	(1,175)
Accumulated other comprehensive loss included the following after-tax balances:
Net loss			226	184
Prior service cost			(60)	(67)
AOCI after-tax balances			166	117
Changes in the benefit obligation:
Benefit obligation — beginning of year			1,175	808
Service cost — benefits earned during the period			39	24	23
Interest cost on projected benefit obligation			37	36	34
Actuarial (gain) loss			73	45
Curtailment (gain) loss			2	10
Special termination benefits			0	0
Benefits paid			(73)	(51)
Sale of Colombia assets			0	0
Additions due to the Acquisition			0	301
Other			6	2
Benefit obligation — end of year			1,259	1,175	808
Changes in plan assets:
Fair value of plan assets — beginning of year			0	0
Actual return on plan assets			0	0
Employer contributions			67	49
Benefits paid			(73)	(51)
Additions due to the Acquisition			0	0
Other			6	2
Fair value of plan assets — end of year			0	0	$ 0
Unfunded status:			$ (1,259)	$ (1,175)