EMPLOYEE BENEFIT PLANS AND POSTRETIREMENT BENEFITS - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Postemployment Benefits [Abstract]
Reduction of plan liability	$ 527	$ 527	$ 527	$ 527
Amortization period of retirement benefits payable	4 years 6 months	4 years 6 months	4 years 6 months	4 years 6 months
Benefits modification amortization	$ 30	$ 30	$ 60	$ 60

Amount of increase (decrease) in benefit obligation of defined benefit plan from change in terms of existing plan or initiation of new plan.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (a)(7)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

Name:	us-gaap_DefinedBenefitPlanPlanAmendments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration