Segment Financial Data (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Segment Reporting Information [Line Items]
Net Sales	$ 15,062	$ 14,354	$ 44,157	$ 42,585
Operating profit	$ 2,163	$ 2,251	$ 6,720	$ 6,533
Operating profit margin	14.40%	15.70%	15.20%	15.30%
Otis [Member]
Segment Reporting Information [Line Items]
Net Sales	$ 3,156	$ 3,018	$ 9,091	$ 8,830
Operating profit	$ 555	$ 584	$ 1,551	$ 1,631
Operating profit margin	17.60%	19.40%	17.10%	18.50%
UTC Climate, Controls & Security [Member]
Segment Reporting Information [Line Items]
Net Sales	$ 4,688	$ 4,415	$ 13,292	$ 12,602
Operating profit	$ 828	$ 801	$ 2,664	$ 2,279
Operating profit margin	17.70%	18.10%	20.00%	18.10%
Pratt & Whitney [Member]
Segment Reporting Information [Line Items]
Net Sales	$ 3,871	$ 3,501	$ 11,699	$ 10,902
Operating profit	$ 229	$ 340	$ 1,024	$ 1,136
Operating profit margin	5.90%	9.70%	8.80%	10.40%
UTC Aerospace Systems [Member]
Segment Reporting Information [Line Items]
Net Sales	$ 3,637	$ 3,646	$ 10,888	$ 10,867
Operating profit	$ 616	$ 600	$ 1,771	$ 1,720
Operating profit margin	16.90%	16.50%	16.30%	15.80%
Total Segments [Member]
Segment Reporting Information [Line Items]
Net Sales	$ 15,352	$ 14,580	$ 44,970	$ 43,201
Operating profit	$ 2,228	$ 2,325	$ 7,010	$ 6,766
Operating profit margin	14.50%	15.90%	15.60%	15.70%
Eliminations and other [Member]
Segment Reporting Information [Line Items]
Net Sales	$ (290)	$ (226)	$ (813)	$ (616)
Operating profit	40	18	25	47
General corporate expenses [Member]
Segment Reporting Information [Line Items]
Net Sales	0	0	0	0
Operating profit	$ (105)	$ (92)	$ (315)	$ (280)