Restructuring and Other Costs (Details) - USD ($) $ in Millions	3 Months Ended				9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Mar. 31, 2019	Sep. 30, 2020	Dec. 31, 2019
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	$ 250				$ 685
Continuing Operations [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	245				680
Cost of Sales [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	142				330
Selling, General and Administrative Expenses [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	103				350
Non-service pension (income) expense
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	5				5
Pratt & Whitney [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	68				175
Collins Aerospace Systems [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	138				295
Eliminations and other [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	44				215
Current Year Actions [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	240				686
Utilization, foreign exchange and other costs	(174)				(225)
Restructuring Reserve	461	$ 395			461	$ 0
Restructuring and Related Cost, Expected Cost [Abstract]
Expected Costs	720				720
Cost Incurred	240	444	$ 2
Remaining Costs	34				34
Current Year Actions [Member] | Severance [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	232				677
Utilization, foreign exchange and other costs	(166)				(216)
Restructuring Reserve	461	395			461	0
Current Year Actions [Member] | Facility Exit, Lease Termination and Other Costs
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	8				9
Utilization, foreign exchange and other costs	(8)				(9)
Restructuring Reserve	0	0			0	0
Current Year Actions [Member] | Cost of Sales [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	139				339
Current Year Actions [Member] | Selling, General and Administrative Expenses [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	96				342
Current Year Actions [Member] | Pratt & Whitney [Member]
Restructuring and Related Cost, Expected Cost [Abstract]
Expected Costs	198				198
Cost Incurred	68	130	0
Remaining Costs	0				0
Current Year Actions [Member] | Collins Aerospace Systems [Member]
Restructuring and Related Cost, Expected Cost [Abstract]
Expected Costs	309				309
Cost Incurred	128	146	1
Remaining Costs	34				34
Current Year Actions [Member] | Eliminations and other [Member]
Restructuring and Related Cost, Expected Cost [Abstract]
Expected Costs	213				213
Cost Incurred	44	168	1
Remaining Costs	0				0
Prior Year Actions [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	9				5
Utilization, foreign exchange and other costs	(10)				(37)
Restructuring Reserve	26	27			26	58
Restructuring and Related Cost, Expected Cost [Abstract]
Expected Costs	229				229
Cost Incurred	9	(9)	5	$ 162
Remaining Costs	62				62
Prior Year Actions [Member] | Severance [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	9				3
Utilization, foreign exchange and other costs	(10)				(34)
Restructuring Reserve	16	17			16	47
Prior Year Actions [Member] | Facility Exit, Lease Termination and Other Costs
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	0				2
Utilization, foreign exchange and other costs	0				(3)
Restructuring Reserve	10	10			10	$ 11
Prior Year Actions [Member] | Cost of Sales [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	2				(5)
Prior Year Actions [Member] | Selling, General and Administrative Expenses [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	7				10
Prior Year Actions [Member] | Pratt & Whitney [Member]
Restructuring and Related Cost, Expected Cost [Abstract]
Expected Costs	121				121
Cost Incurred	0	(12)	0	133
Remaining Costs	0				0
Prior Year Actions [Member] | Collins Aerospace Systems [Member]
Restructuring and Related Cost, Expected Cost [Abstract]
Expected Costs	106				106
Cost Incurred	9	3	5	27
Remaining Costs	62				62
Prior Year Actions [Member] | Eliminations and other [Member]
Restructuring and Related Cost, Expected Cost [Abstract]
Expected Costs	2				2
Cost Incurred	0	$ 0	$ 0	$ 2
Remaining Costs	0				0
Two Years Prior Actions [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	1				(6)
Restructuring Reserve	$ 51				$ 51