Restructuring and Other Costs (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended	12 Months Ended
	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Sep. 30, 2017	Dec. 31, 2016
Restructuring Cost and Reserve [Line Items]
Restructuring Charges				$ 177
Cost of Sales [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges				81
Selling, General and Administrative Expenses [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges				96
Current Year Actions [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges				114
Restructuring Reserve	$ 72	$ 43		72
Net pre-tax restructuring costs (reversals)	51	39	$ 24	114
Utilization and foreign exchange	22			42
Expected Costs	218			218
Remaining Costs	104			104
Current Year Actions [Member] | Cost of Sales [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges				40
Current Year Actions [Member] | Selling, General and Administrative Expenses [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges				74
Current Year Actions [Member] | Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	72	43		72
Net pre-tax restructuring costs (reversals)	49			106
Utilization and foreign exchange	20			34
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)	2			8
Utilization and foreign exchange	2			8
Prior Year Actions [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges				48
Restructuring Reserve	92	97		92	$ 109
Net pre-tax restructuring costs (reversals)	8	18	22	48	242
Utilization and foreign exchange	13			65
Expected Costs	340			340
Remaining Costs	50			50
Prior Year Actions [Member] | Cost of Sales [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges				20
Prior Year Actions [Member] | Selling, General and Administrative Expenses [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges				28
Prior Year Actions [Member] | Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	40	49		40	63
Net pre-tax restructuring costs (reversals)	3			29
Utilization and foreign exchange	12			52
Prior Year Actions [Member] | Facility Exit, Lease Termination and Other Costs
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	52	48		52	46
Net pre-tax restructuring costs (reversals)	5			19
Utilization and foreign exchange	1			13
Two Years Prior Actions [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges				15
Restructuring Reserve	52			52
Otis [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges				23
Otis [Member] | Current Year Actions [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs (reversals)	5	12	2
Expected Costs	71			71
Remaining Costs	52			52
Otis [Member] | Prior Year Actions [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs (reversals)	0	(1)	3		48
Expected Costs	55			55
Remaining Costs	5			5
UTC Climate, Controls & Security [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges				84
UTC Climate, Controls & Security [Member] | Current Year Actions [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs (reversals)	35	11	12
Expected Costs	83			83
Remaining Costs	25			25
UTC Climate, Controls & Security [Member] | Prior Year Actions [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs (reversals)	3	7	6		45
Expected Costs	80			80
Remaining Costs	19			19
Pratt & Whitney [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges				4
Pratt & Whitney [Member] | Current Year Actions [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs (reversals)	0	6	0
Expected Costs	8			8
Remaining Costs	2			2
Pratt & Whitney [Member] | Prior Year Actions [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs (reversals)	0	0	0		118
Expected Costs	118			118
Remaining Costs	0			0
UTC Aerospace Systems [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges				64
UTC Aerospace Systems [Member] | Current Year Actions [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs (reversals)	10	10	9
Expected Costs	54			54
Remaining Costs	25			25
UTC Aerospace Systems [Member] | Prior Year Actions [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs (reversals)	5	$ 12	13		$ 31
Expected Costs	87			87
Remaining Costs	26			26
Eliminations and other [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges				2
Eliminations and other [Member] | Current Year Actions [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs (reversals)	(1)		$ (1)
Expected Costs	2			2
Remaining Costs	$ 0			$ 0