Acquisition, Dispositions, Goodwill and Other Intangible Assets (Goodwill) (Details) $ in Millions	6 Months Ended
	Jun. 30, 2017 USD ($)
Goodwill [Line Items]
Goodwill - Beginning Balance	$ 27,059
Goodwill Resulting from Business Combinations	94
Goodwill - Foreign Currency Translation and Other	434
Goodwill - Ending Balance	27,587
Otis [Member]
Goodwill [Line Items]
Goodwill - Beginning Balance	1,575
Goodwill Resulting from Business Combinations	(1)
Goodwill - Foreign Currency Translation and Other	78
Goodwill - Ending Balance	1,652
UTC Climate, Controls & Security [Member]
Goodwill [Line Items]
Goodwill - Beginning Balance	9,487
Goodwill Resulting from Business Combinations	95
Goodwill - Foreign Currency Translation and Other	256
Goodwill - Ending Balance	9,838
Pratt & Whitney [Member]
Goodwill [Line Items]
Goodwill - Beginning Balance	1,511
Goodwill Resulting from Business Combinations	0
Goodwill - Foreign Currency Translation and Other	0
Goodwill - Ending Balance	1,511
UTC Aerospace Systems [Member]
Goodwill [Line Items]
Goodwill - Beginning Balance	14,483
Goodwill Resulting from Business Combinations	0
Goodwill - Foreign Currency Translation and Other	100
Goodwill - Ending Balance	14,583
Total Segments [Member]
Goodwill [Line Items]
Goodwill - Beginning Balance	27,056
Goodwill Resulting from Business Combinations	94
Goodwill - Foreign Currency Translation and Other	434
Goodwill - Ending Balance	27,584
Eliminations and other [Member]
Goodwill [Line Items]
Goodwill - Beginning Balance	3
Goodwill Resulting from Business Combinations	0
Goodwill - Foreign Currency Translation and Other	0
Goodwill - Ending Balance	$ 3