Restructuring and Other Costs (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2019
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	$ 19
Cost of Sales [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	6
Selling, General and Administrative Expenses [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	13
Otis [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	6
Carrier [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	5
Pratt & Whitney [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	0
Collins Aerospace Systems [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	6
Eliminations and other [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	2
Current Year Actions [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	8
Utilization, foreign exchange and other costs	(3)
Restructuring Reserve	5
Restructuring and Related Cost, Expected Cost [Abstract]
Expected Costs	17
Cost Incurred		$ 8
Remaining Costs	9
Current Year Actions [Member] | Severance [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	8
Utilization, foreign exchange and other costs	(3)
Restructuring Reserve	5
Current Year Actions [Member] | Facility Exit, Lease Termination and Other Costs
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	0
Utilization, foreign exchange and other costs	0
Restructuring Reserve	0
Current Year Actions [Member] | Cost of Sales [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	2
Current Year Actions [Member] | Selling, General and Administrative Expenses [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	6
Current Year Actions [Member] | Otis [Member]
Restructuring and Related Cost, Expected Cost [Abstract]
Expected Costs	5
Cost Incurred		4
Remaining Costs	1
Current Year Actions [Member] | Carrier [Member]
Restructuring and Related Cost, Expected Cost [Abstract]
Expected Costs	4
Cost Incurred		2
Remaining Costs	2
Current Year Actions [Member] | Pratt & Whitney [Member]
Restructuring and Related Cost, Expected Cost [Abstract]
Expected Costs	0
Cost Incurred		0
Remaining Costs	0
Current Year Actions [Member] | Collins Aerospace Systems [Member]
Restructuring and Related Cost, Expected Cost [Abstract]
Expected Costs	6
Cost Incurred		1
Remaining Costs	5
Current Year Actions [Member] | Eliminations and other [Member]
Restructuring and Related Cost, Expected Cost [Abstract]
Expected Costs	2
Cost Incurred		1
Remaining Costs	1
Prior Year Actions [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	10
Utilization, foreign exchange and other costs	(38)
Restructuring Reserve	90			$ 118
Restructuring and Related Cost, Expected Cost [Abstract]
Expected Costs	440
Cost Incurred		10	$ 321
Remaining Costs	109
Prior Year Actions [Member] | Severance [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	8
Utilization, foreign exchange and other costs	(35)
Restructuring Reserve	78			105
Prior Year Actions [Member] | Facility Exit, Lease Termination and Other Costs
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	2
Utilization, foreign exchange and other costs	(3)
Restructuring Reserve	12			$ 13
Prior Year Actions [Member] | Cost of Sales [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	2
Prior Year Actions [Member] | Selling, General and Administrative Expenses [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	8
Prior Year Actions [Member] | Otis [Member]
Restructuring and Related Cost, Expected Cost [Abstract]
Expected Costs	63
Cost Incurred		2	45
Remaining Costs	16
Prior Year Actions [Member] | Carrier [Member]
Restructuring and Related Cost, Expected Cost [Abstract]
Expected Costs	120
Cost Incurred		3	110
Remaining Costs	7
Prior Year Actions [Member] | Pratt & Whitney [Member]
Restructuring and Related Cost, Expected Cost [Abstract]
Expected Costs	133
Cost Incurred		0	133
Remaining Costs	0
Prior Year Actions [Member] | Collins Aerospace Systems [Member]
Restructuring and Related Cost, Expected Cost [Abstract]
Expected Costs	118
Cost Incurred		5	27
Remaining Costs	86
Prior Year Actions [Member] | Eliminations and other [Member]
Restructuring and Related Cost, Expected Cost [Abstract]
Expected Costs	6
Cost Incurred		$ 0	$ 6
Remaining Costs	0
Two Years Prior Actions [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	1
Restructuring Reserve	$ 58