OPERATING SEGMENTS - Reconciliation of Assets, Property, Plant and Equipment Additions and Depreciation and Amortization (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Assets	$ 253,452	$ 265,177
Equity in earnings (loss) of affiliates	104	423	$ (233)
Capital
Segment Reporting Information [Line Items]
Equity in earnings (loss) of affiliates	77	217	(254)
Continuing Operations
Segment Reporting Information [Line Items]
Assets	249,920	261,068	246,686
Property, plant and equipment additions	3,252	5,813	6,632
Depreciation and amortization	6,018	5,595	6,582
Continuing Operations | Operating segments | Capital
Segment Reporting Information [Line Items]
Assets	113,526	117,546	119,329
Property, plant and equipment additions	1,765	3,830	4,569
Depreciation and amortization	2,590	2,083	2,163
Continuing Operations | Corporate items and eliminations
Segment Reporting Information [Line Items]
Assets	35,151	29,269	18,043
Property, plant and equipment additions	(51)	(175)	(46)
Depreciation and amortization	494	355	763
Power | Operating segments | Industrial segment
Segment Reporting Information [Line Items]
Equity in earnings (loss) of affiliates	43	(4)	(20)
Power | Continuing Operations | Operating segments | Industrial segment
Segment Reporting Information [Line Items]
Assets	24,453	26,731	27,389
Property, plant and equipment additions	245	277	358
Depreciation and amortization	749	880	1,307
Renewable Energy | Operating segments | Industrial segment
Segment Reporting Information [Line Items]
Equity in earnings (loss) of affiliates	13	(2)	(1)
Renewable Energy | Continuing Operations | Operating segments | Industrial segment
Segment Reporting Information [Line Items]
Assets	15,927	15,935	16,400
Property, plant and equipment additions	302	455	303
Depreciation and amortization	413	425	474
Aviation | Operating segments | Industrial segment
Segment Reporting Information [Line Items]
Equity in earnings (loss) of affiliates	(41)	204	126
Aviation | Continuing Operations | Operating segments | Industrial segment
Segment Reporting Information [Line Items]
Assets	38,634	41,083	37,488
Property, plant and equipment additions	737	1,031	1,070
Depreciation and amortization	1,142	1,150	1,042
Healthcare | Operating segments | Industrial segment
Segment Reporting Information [Line Items]
Equity in earnings (loss) of affiliates	7	19	16
Healthcare | Continuing Operations | Operating segments | Industrial segment
Segment Reporting Information [Line Items]
Assets	22,229	30,503	28,037
Property, plant and equipment additions	256	395	378
Depreciation and amortization	$ 628	$ 702	$ 832