Restructuring Costs (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended	12 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2021	Dec. 31, 2020
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	$ 56		$ 99
Cost of Sales [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	1		21
Selling, General and Administrative Expenses [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	55		78
Pratt & Whitney [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	(16)		4
Collins Aerospace Systems [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	12		30
Eliminations and other [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	60		65
Current Year Actions [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	65		101
Utilization, foreign exchange and other costs	(27)		(31)
Restructuring Reserve	70	$ 32	70	$ 0
Restructuring and Related Cost, Expected Cost [Abstract]
Expected Costs	147		147
Costs Incurred	(65)	(36)
Remaining Costs	46		46
Current Year Actions [Member] | Severance [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	63		87
Utilization, foreign exchange and other costs	(25)		(26)
Restructuring Reserve	61	23	61	0
Current Year Actions [Member] | Facility Exit, Lease Termination and Other Costs
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	2		14
Utilization, foreign exchange and other costs	(2)		(5)
Restructuring Reserve	9	9	9	0
Current Year Actions [Member] | Cost of Sales [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	4		25
Current Year Actions [Member] | Selling, General and Administrative Expenses [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	61		76
Current Year Actions [Member] | Pratt & Whitney [Member]
Restructuring and Related Cost, Expected Cost [Abstract]
Expected Costs	25		25
Costs Incurred	(2)	(20)
Remaining Costs	3		3
Current Year Actions [Member] | Collins Aerospace Systems [Member]
Restructuring and Related Cost, Expected Cost [Abstract]
Expected Costs	62		62
Costs Incurred	(3)	(16)
Remaining Costs	43		43
Current Year Actions [Member] | Eliminations and other [Member]
Restructuring and Related Cost, Expected Cost [Abstract]
Expected Costs	60		60
Costs Incurred	(60)	0
Remaining Costs	0		0
Prior Year Actions [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	(24)		(20)
Utilization, foreign exchange and other costs	(59)		(194)
Restructuring Reserve	126	209	126	340
Restructuring and Related Cost, Expected Cost [Abstract]
Expected Costs	759		759
Costs Incurred	24	(4)		(770)
Remaining Costs	9		9
Prior Year Actions [Member] | Severance [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	(27)		(26)
Utilization, foreign exchange and other costs	(105)		(235)
Restructuring Reserve	73	205	73	334
Prior Year Actions [Member] | Facility Exit, Lease Termination and Other Costs
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	3		6
Utilization, foreign exchange and other costs	46		41
Restructuring Reserve	53	4	53	6
Prior Year Actions [Member] | Cost of Sales [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	(6)		(8)
Prior Year Actions [Member] | Selling, General and Administrative Expenses [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	(18)		(12)
Prior Year Actions [Member] | Pratt & Whitney [Member]
Restructuring and Related Cost, Expected Cost [Abstract]
Expected Costs	188		188
Costs Incurred	17	0		(205)
Remaining Costs	0		0
Prior Year Actions [Member] | Collins Aerospace Systems [Member]
Restructuring and Related Cost, Expected Cost [Abstract]
Expected Costs	334		334
Costs Incurred	7	1		(333)
Remaining Costs	9		9
Prior Year Actions [Member] | Eliminations and other [Member]
Restructuring and Related Cost, Expected Cost [Abstract]
Expected Costs	237		237
Costs Incurred	0	$ (5)		$ (232)
Remaining Costs	0		0
Two Years Prior Actions [Member]
Restructuring Cost and Reserve [Line Items]
Net pre-tax restructuring costs	15		18
Restructuring Reserve	$ 31		$ 31