ACQUISITIONS, GOODWILL AND OTHER INTANGIBLE ASSETS - Changes in Goodwill Balances (Details) $ in Millions	6 Months Ended
	Jun. 30, 2018 USD ($)
Goodwill
Balance at beginning of period	$ 83,968
Acquisitions	0
Dispositions, currency exchange and other	(1,504)
Balance at end of period	82,464
Operating Segments | Power
Goodwill
Balance at beginning of period	25,269
Acquisitions	0
Dispositions, currency exchange and other	(2,083)
Balance at end of period	23,186
Operating Segments | Renewable Energy
Goodwill
Balance at beginning of period	4,093
Acquisitions	0
Dispositions, currency exchange and other	(31)
Balance at end of period	4,062
Operating Segments | Oil & Gas
Goodwill
Balance at beginning of period	23,943
Acquisitions	0
Dispositions, currency exchange and other	673
Balance at end of period	24,616
Operating Segments | Aviation
Goodwill
Balance at beginning of period	10,008
Acquisitions	0
Dispositions, currency exchange and other	(36)
Balance at end of period	9,972
Operating Segments | Healthcare
Goodwill
Balance at beginning of period	17,306
Acquisitions	0
Dispositions, currency exchange and other	(35)
Balance at end of period	17,272
Operating Segments | Transportation
Goodwill
Balance at beginning of period	902
Acquisitions	0
Dispositions, currency exchange and other	(8)
Balance at end of period	894
Operating Segments | Lighting
Goodwill
Balance at beginning of period	0
Acquisitions	0
Dispositions, currency exchange and other	0
Balance at end of period	0
Operating Segments | Capital
Goodwill
Balance at beginning of period	984
Acquisitions	0
Dispositions, currency exchange and other	0
Balance at end of period	984
Corporate
Goodwill
Balance at beginning of period	1,463
Acquisitions	0
Dispositions, currency exchange and other	15
Balance at end of period	$ 1,478