Segment Financial Data (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Segment Reporting Information [Line Items]
Net Sales	$ 15,280	$ 14,874	$ 29,095	$ 28,231
Operating profit	$ 2,290	$ 2,337	$ 4,557	$ 4,282
Operating profit margin	15.00%	15.70%	15.70%	15.20%
Otis [Member]
Segment Reporting Information [Line Items]
Net Sales	$ 3,131	$ 3,097	$ 5,935	$ 5,812
Operating profit	$ 544	$ 581	$ 996	$ 1,047
Operating profit margin	17.40%	18.80%	16.80%	18.00%
UTC Climate, Controls & Security [Member]
Segment Reporting Information [Line Items]
Net Sales	$ 4,712	$ 4,459	$ 8,604	$ 8,187
Operating profit	$ 873	$ 872	$ 1,836	$ 1,478
Operating profit margin	18.50%	19.60%	21.30%	18.10%
Pratt & Whitney [Member]
Segment Reporting Information [Line Items]
Net Sales	$ 4,070	$ 3,813	$ 7,828	$ 7,401
Operating profit	$ 402	$ 386	$ 795	$ 796
Operating profit margin	9.90%	10.10%	10.20%	10.80%
UTC Aerospace Systems [Member]
Segment Reporting Information [Line Items]
Net Sales	$ 3,640	$ 3,716	$ 7,251	$ 7,221
Operating profit	$ 579	$ 582	$ 1,155	$ 1,120
Operating profit margin	15.90%	15.70%	15.90%	15.50%
Total Segments [Member]
Segment Reporting Information [Line Items]
Net Sales	$ 15,553	$ 15,085	$ 29,618	$ 28,621
Operating profit	$ 2,398	$ 2,421	$ 4,782	$ 4,441
Operating profit margin	15.40%	16.00%	16.10%	15.50%
Eliminations and other [Member]
Segment Reporting Information [Line Items]
Net Sales	$ (273)	$ (211)	$ (523)	$ (390)
Operating profit	(2)	13	(15)	29
General corporate expenses [Member]
Segment Reporting Information [Line Items]
Net Sales	0	0	0	0
Operating profit	$ (106)	$ (97)	$ (210)	$ (188)