POSTRETIREMENT BENEFIT PLANS - Composition of Plan Assets, Pension Plans (Narrative) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 80,483,000	$ 72,064,000
Principal pension
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	58,843,000	52,633,000	$ 50,009,000
Principal pension | GE Pension Plan | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,721,000	2,838,000
Other pension
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	21,506,000	19,142,000	17,537,000
Other pension | GE Pension Plan | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	97,000	105,000
Principal retiree benefit plans
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 134,000	$ 289,000	$ 362,000