RETIREMENT AND POSTRETIREMENT BENEFIT PLANS - COMPONENTS OF NET PERIODIC BENEFIT COST (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Pension Benefits
Net periodic benefit costs:
Service cost — benefits earned during the period	$ 45	$ 5	$ 6
Interest cost on projected benefit obligation	39	15	17
Expected return on plan assets	(50)	(25)	(24)
Recognized actuarial loss	9	7	10
Recognized prior service credit	0	0	0
Liability (gain) loss due to curtailment	(91)	0	0
Special termination benefits	49	0	0
Other costs and adjustments	(2)	1	3
Net periodic benefit cost	(1)	3	12
Amounts that will be amortized from AOCI into net periodic benefit cost over the next fiscal year
Estimated net loss that will be amortized from AOCI into net periodic benefit cost over the next fiscal year	3
Estimated prior service cost that will be amortized from AOCI into net periodic benefit cost over the next fiscal year	0
Postretirement Benefits
Net periodic benefit costs:
Service cost — benefits earned during the period	24	23	21
Interest cost on projected benefit obligation	36	34	38
Expected return on plan assets	0	0	0
Recognized actuarial loss	8	14	14
Recognized prior service credit	(8)	0	0
Liability (gain) loss due to curtailment	6	0	0
Special termination benefits	0	0	0
Other costs and adjustments	0	(2)	1
Net periodic benefit cost	66	$ 69	$ 74
Amounts that will be amortized from AOCI into net periodic benefit cost over the next fiscal year
Estimated net loss that will be amortized from AOCI into net periodic benefit cost over the next fiscal year	12
Estimated prior service cost that will be amortized from AOCI into net periodic benefit cost over the next fiscal year	$ (8)