ALL OTHER ASSETS - Equity Method Investments (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Entity Information [Line Items]
Equity method investment balance	$ 6,724	$ 5,700
Equity method income (loss)	104	423	$ (233)
Capital
Entity Information [Line Items]
Equity method investment balance	3,110	2,159
Equity method income (loss)	77	217	(254)
Increase in equity method investments	951
Operating segments | Industrial segment | Power
Entity Information [Line Items]
Equity method investment balance	576	565
Equity method income (loss)	43	(4)	(20)
Operating segments | Industrial segment | Renewable Energy
Entity Information [Line Items]
Equity method investment balance	724	630
Equity method income (loss)	13	(2)	(1)
Operating segments | Industrial segment | Aviation
Entity Information [Line Items]
Equity method investment balance	2,032	2,073
Equity method income (loss)	(41)	204	126
Operating segments | Industrial segment | Healthcare
Entity Information [Line Items]
Equity method investment balance	251	245
Equity method income (loss)	7	19	16
Corporate items and eliminations
Entity Information [Line Items]
Equity method investment balance	31	28
Equity method income (loss)	$ 5	$ (11)	$ (99)