Restructuring and Other Costs (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended	12 Months Ended
	Jun. 30, 2017	Mar. 31, 2017	Jun. 30, 2017	Dec. 31, 2016
Restructuring Cost and Reserve [Line Items]
Restructuring Charges			$ 112
Cost of Sales [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges			50
Selling, General and Administrative Expenses [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges			62
Current Year Actions [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges			63
Restructuring Reserve	$ 43	$ 16	43
Net pre-tax restructuring costs (reversals)	39	24	63
Utilization and foreign exchange	12		20
Expected Costs	128		128
Remaining Costs	65		65
Current Year Actions [Member] | Cost of Sales [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges			21
Current Year Actions [Member] | Selling, General and Administrative Expenses [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges			42
Current Year Actions [Member] | Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	43	16	43
Net pre-tax restructuring costs (reversals)	36		57
Utilization and foreign exchange	9		14
Current Year Actions [Member] | Facility Exit, Lease Termination and Other Costs
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	0	0	0
Net pre-tax restructuring costs (reversals)	3		6
Utilization and foreign exchange	3		6
Prior Year Actions [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges			40
Restructuring Reserve	97	103	97	$ 109
Net pre-tax restructuring costs (reversals)	18	22	40	242
Utilization and foreign exchange	24		52
Expected Costs	341		341
Remaining Costs	59		59
Prior Year Actions [Member] | Cost of Sales [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges			16
Prior Year Actions [Member] | Selling, General and Administrative Expenses [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges			24
Prior Year Actions [Member] | Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	49	56	49	63
Net pre-tax restructuring costs (reversals)	11		26
Utilization and foreign exchange	18		40
Prior Year Actions [Member] | Facility Exit, Lease Termination and Other Costs
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	48	47	48	46
Net pre-tax restructuring costs (reversals)	7		14
Utilization and foreign exchange	6		12
Two Years Prior Actions [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges			9
Restructuring Reserve	69		69
Otis [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges			17
Otis [Member] | Current Year Actions [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs (reversals)	12	2
Expected Costs	29		29
Remaining Costs	15		15
Otis [Member] | Prior Year Actions [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs (reversals)	(1)	3		48
Expected Costs	55		55
Remaining Costs	5		5
UTC Climate, Controls & Security [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges			41
UTC Climate, Controls & Security [Member] | Current Year Actions [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs (reversals)	11	12
Expected Costs	37		37
Remaining Costs	14		14
UTC Climate, Controls & Security [Member] | Prior Year Actions [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs (reversals)	7	6		45
Expected Costs	83		83
Remaining Costs	25		25
Pratt & Whitney [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges			6
Pratt & Whitney [Member] | Current Year Actions [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs (reversals)	6	0
Expected Costs	6		6
Remaining Costs	0		0
Pratt & Whitney [Member] | Prior Year Actions [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs (reversals)	0	0		118
Expected Costs	118		118
Remaining Costs	0		0
UTC Aerospace Systems [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges			47
UTC Aerospace Systems [Member] | Current Year Actions [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs (reversals)	10	9
Expected Costs	55		55
Remaining Costs	36		36
UTC Aerospace Systems [Member] | Prior Year Actions [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs (reversals)	12	13		$ 31
Expected Costs	85		85
Remaining Costs	29		29
Eliminations and other [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges			1
Eliminations and other [Member] | Current Year Actions [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs (reversals)		$ (1)
Expected Costs	1		1
Remaining Costs	$ 0		$ 0