Acquisition, Dispositions, Goodwill and Other Intangible Assets (Goodwill) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2017 USD ($)
Goodwill [Line Items]
Goodwill - Beginning Balance	$ 27,059
Goodwill Resulting from Business Combinations	34
Goodwill - Foreign Currency Translation and Other	180
Goodwill - Ending Balance	27,273
Otis [Member]
Goodwill [Line Items]
Goodwill - Beginning Balance	1,575
Goodwill Resulting from Business Combinations	(7)
Goodwill - Foreign Currency Translation and Other	57
Goodwill - Ending Balance	1,625
UTC Climate, Controls & Security [Member]
Goodwill [Line Items]
Goodwill - Beginning Balance	9,487
Goodwill Resulting from Business Combinations	41
Goodwill - Foreign Currency Translation and Other	93
Goodwill - Ending Balance	9,621
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	30
Goodwill - Ending Balance	14,513
Total Segments [Member]
Goodwill [Line Items]
Goodwill - Beginning Balance	27,056
Goodwill Resulting from Business Combinations	34
Goodwill - Foreign Currency Translation and Other	180
Goodwill - Ending Balance	27,270
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