Restructuring and Other Costs (Details) - USD ($) $ in Millions	3 Months Ended				9 Months Ended		12 Months Ended
	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Restructuring Cost and Reserve [Line Items]
Restructuring costs recorded within continuing operations					$ 205
Restructuring costs recorded within discontinued operations					139
Total restructuring costs					344
Disposal Group, Including Discontinued Operation, Recognized Net (Gain) Loss Due to Curtailments	$ 110			$ 0	110	$ 0
Restructuring Reserve, Two Years Prior Actions	42				42
Current Year Actions [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring costs recorded within continuing operations	166				271
Restructuring Reserve Beginning Balance	89
Utilization and foreign exchange	164
Restructuring Reserve Ending Balance	91	$ 89			91
Restructuring and Related Cost, Incurred Cost	166	41	$ 64
Restructuring and Related Cost, Expected Cost	331				331
Restructuring And Related Cost Expected Remaining	60				60
Current Year Actions [Member] | Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring costs recorded within continuing operations	157
Restructuring Reserve Beginning Balance	89
Utilization and foreign exchange	157
Restructuring Reserve Ending Balance	89	89			89
Current Year Actions [Member] | Facility Exit, Lease Termination and Other Costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring costs recorded within continuing operations	9
Restructuring Reserve Beginning Balance	0
Utilization and foreign exchange	7
Restructuring Reserve Ending Balance	2	0			2
Prior Year Actions [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring costs recorded within continuing operations	25				73
Restructuring Reserve Beginning Balance	129
Utilization and foreign exchange	33
Restructuring Reserve Ending Balance	121	129			121
Restructuring and Related Cost, Incurred Cost	25	25	23				$ 345
Restructuring and Related Cost, Expected Cost	482				482
Restructuring And Related Cost Expected Remaining	64				64
Prior Year Actions [Member] | Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring costs recorded within continuing operations	19
Restructuring Reserve Beginning Balance	123
Utilization and foreign exchange	24
Restructuring Reserve Ending Balance	118	123			118
Prior Year Actions [Member] | Facility Exit, Lease Termination and Other Costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring costs recorded within continuing operations	6
Restructuring Reserve Beginning Balance	6
Utilization and foreign exchange	9
Restructuring Reserve Ending Balance	3	6			3
Otis [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring costs recorded within continuing operations					32
Otis [Member] | Current Year Actions [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost	12	4	0
Restructuring and Related Cost, Expected Cost	26				26
Restructuring And Related Cost Expected Remaining	10				10
Otis [Member] | Prior Year Actions [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost	6	4	6				98
Restructuring and Related Cost, Expected Cost	129				129
Restructuring And Related Cost Expected Remaining	15				15
UTC Climate, Controls & Security [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring costs recorded within continuing operations					67
UTC Climate, Controls & Security [Member] | Current Year Actions [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost	11	12	16
Restructuring and Related Cost, Expected Cost	49				49
Restructuring And Related Cost Expected Remaining	10				10
UTC Climate, Controls & Security [Member] | Prior Year Actions [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost	5	18	7				86
Restructuring and Related Cost, Expected Cost	127				127
Restructuring And Related Cost Expected Remaining	11				11
Pratt & Whitney [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring costs recorded within continuing operations					37
Pratt & Whitney [Member] | Current Year Actions [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost	10	2	1
Restructuring and Related Cost, Expected Cost	19				19
Restructuring And Related Cost Expected Remaining	6				6
Pratt & Whitney [Member] | Prior Year Actions [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost	13	2	10				64
Restructuring and Related Cost, Expected Cost	118				118
Restructuring And Related Cost Expected Remaining	29				29
UTC Aerospace Systems [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring costs recorded within continuing operations					64
UTC Aerospace Systems [Member] | Current Year Actions [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost	13	(4)	47
Restructuring and Related Cost, Expected Cost	68				68
Restructuring And Related Cost Expected Remaining	12				12
UTC Aerospace Systems [Member] | Prior Year Actions [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost	1	1	0				72
Restructuring and Related Cost, Expected Cost	83				83
Restructuring And Related Cost Expected Remaining	9				9
Eliminations and other [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring costs recorded within continuing operations					5
Eliminations and other [Member] | Current Year Actions [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost	4	1	0
Restructuring and Related Cost, Expected Cost	5				5
Restructuring And Related Cost Expected Remaining	0				0
Eliminations and other [Member] | Prior Year Actions [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost	0	0	0				5
Restructuring and Related Cost, Expected Cost	5				5
Restructuring And Related Cost Expected Remaining	0				0
Discontinued Operations [Member] | Current Year Actions [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring costs recorded within continuing operations					142
Restructuring and Related Cost, Incurred Cost	116	26	0
Restructuring and Related Cost, Expected Cost	164				164
Restructuring And Related Cost Expected Remaining	22				22
Discontinued Operations [Member] | Prior Year Actions [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost	0	$ 0	$ 0				$ 20
Restructuring and Related Cost, Expected Cost	20				20
Restructuring And Related Cost Expected Remaining	$ 0				0
Cost Of Sales [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring costs recorded within continuing operations					106
Cost Of Sales [Member] | Current Year Actions [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring costs recorded within continuing operations					61
Cost Of Sales [Member] | Prior Year Actions [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring costs recorded within continuing operations					44
Selling General and Administrative [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring costs recorded within continuing operations					99
Selling General and Administrative [Member] | Current Year Actions [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring costs recorded within continuing operations					68
Selling General and Administrative [Member] | Prior Year Actions [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring costs recorded within continuing operations					$ 29