Restructuring and Other Costs (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	$ 112
Cost of Sales [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	56
Selling, General and Administrative Expenses [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	56
Otis [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	25
Carrier [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	33
Pratt & Whitney [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	14
Collins Aerospace Systems [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	39
Eliminations and other [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	1
Current Year Actions [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	73
Utilization, foreign exchange and other costs	(5)
Restructuring Reserve	68
Restructuring and Related Cost, Expected Cost [Abstract]
Expected Costs	104
Cost Incurred	(73)
Remaining Costs	31
Current Year Actions [Member] | Severance [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	68
Utilization, foreign exchange and other costs	(15)
Restructuring Reserve	53
Current Year Actions [Member] | Facility Exit, Lease Termination and Other Costs
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	5
Utilization, foreign exchange and other costs	10
Restructuring Reserve	15
Current Year Actions [Member] | Cost of Sales [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	28
Current Year Actions [Member] | Selling, General and Administrative Expenses [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	45
Current Year Actions [Member] | Otis [Member]
Restructuring and Related Cost, Expected Cost [Abstract]
Expected Costs	27
Cost Incurred	(19)
Remaining Costs	8
Current Year Actions [Member] | Carrier [Member]
Restructuring and Related Cost, Expected Cost [Abstract]
Expected Costs	40
Cost Incurred	(25)
Remaining Costs	15
Current Year Actions [Member] | Pratt & Whitney [Member]
Restructuring and Related Cost, Expected Cost [Abstract]
Expected Costs	14
Cost Incurred	(14)
Remaining Costs	0
Current Year Actions [Member] | Collins Aerospace Systems [Member]
Restructuring and Related Cost, Expected Cost [Abstract]
Expected Costs	22
Cost Incurred	(14)
Remaining Costs	8
Current Year Actions [Member] | Eliminations and other [Member]
Restructuring and Related Cost, Expected Cost [Abstract]
Expected Costs	1
Cost Incurred	(1)
Remaining Costs	0
Prior Year Actions [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	23
Utilization, foreign exchange and other costs	(90)
Restructuring Reserve	71	$ 138
Restructuring and Related Cost, Expected Cost [Abstract]
Expected Costs	286
Cost Incurred	(23)	(207)
Remaining Costs	56
Prior Year Actions [Member] | Severance [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	21
Utilization, foreign exchange and other costs	(74)
Restructuring Reserve	62	115
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	(16)
Restructuring Reserve	9	23
Prior Year Actions [Member] | Cost of Sales [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	16
Prior Year Actions [Member] | Selling, General and Administrative Expenses [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	7
Prior Year Actions [Member] | Otis [Member]
Restructuring and Related Cost, Expected Cost [Abstract]
Expected Costs	58
Cost Incurred	(5)	(48)
Remaining Costs	5
Prior Year Actions [Member] | Carrier [Member]
Restructuring and Related Cost, Expected Cost [Abstract]
Expected Costs	107
Cost Incurred	(7)	(64)
Remaining Costs	36
Prior Year Actions [Member] | Pratt & Whitney [Member]
Restructuring and Related Cost, Expected Cost [Abstract]
Expected Costs	3
Cost Incurred	0	(3)
Remaining Costs	0
Prior Year Actions [Member] | Collins Aerospace Systems [Member]
Restructuring and Related Cost, Expected Cost [Abstract]
Expected Costs	113
Cost Incurred	(11)	(87)
Remaining Costs	15
Prior Year Actions [Member] | Eliminations and other [Member]
Restructuring and Related Cost, Expected Cost [Abstract]
Expected Costs	5
Cost Incurred	0	$ (5)
Remaining Costs	0
Two Years Prior Actions [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	16
Restructuring Reserve	$ 103