Business Combinations (Details) - USD ($) $ in Millions			1 Months Ended				3 Months Ended		12 Months Ended
	Jan. 08, 2021	Apr. 03, 2020	Nov. 30, 2021	Sep. 30, 2021	Dec. 31, 2020	May 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Business Acquisition [Line Items]
Acquisition Cost Of Acquired Entities and Interest in Affiliates									$ 1,100	$ 35,100	$ 9
Customer Contractual Obligation					$ 1,243				929	1,243
Goodwill, Acquired During Period			$ 800						566
Payments to Acquire Businesses, Net of Cash Acquired			1,100
Finite-lived Intangible Assets Acquired			$ 300
Proceeds from Divestiture of Businesses and Interests in Affiliates				$ 900					1,879	2,556	134
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal				251
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal, After Tax				135
Disposal Group, Not Discontinued Operation, Gain (Loss) on Non-Service Pension (Income) Expense				$ 12
Total Assets					162,153				161,404	162,153
Liabilities					88,269				86,705	88,269
Goodwill, Impairment Loss								$ 3,200	0	3,183	0
Amortization of Intangible Assets									2,439	2,125	$ 1,244
Collins Aerospace Military Global Positioning System G P S And Space Based Precision Optics Businesses [Member]
Business Acquisition [Line Items]
Costs related to the divestitures required for regulatory approval							$ 20
Proceeds from Divestiture of Businesses and Interests in Affiliates							2,300
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal							580
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal, After Tax							253
Collins Aerospace Military Global Positioning System G P S And Space Based Precision Optics Businesses [Member] | Other Income (Expense) [Member]
Business Acquisition [Line Items]
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal							608
Collins Aerospace Military Global Positioning System G P S And Space Based Precision Optics Businesses [Member] | Nonoperating Income (Expense)
Business Acquisition [Line Items]
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal							$ 8
Airborne tactical radios business [Member]
Business Acquisition [Line Items]
Proceeds from Divestiture of Businesses and Interests in Affiliates						$ 231
Gain on disposal recorded as an adjustment to fair value of net asset acquired						$ 199
Forcepoint [Member]
Business Acquisition [Line Items]
Proceeds from Divestiture of Businesses and Interests in Affiliates	$ 1,100
Forcepoint [Member] | Disposal Group, Held-for-sale, Not Discontinued Operations [Member]
Business Acquisition [Line Items]
Total Assets					1,900					1,900
Liabilities					855					855
Goodwill and intangible assets					1,400					1,400
Collins Aerospace Systems [Member]
Business Acquisition [Line Items]
Goodwill, Acquired During Period									228
Total Assets					68,701				$ 67,564	68,701
Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount									15.00%
Goodwill, Impairment Loss								$ 3,200		3,200
Impairment of Intangible Assets (Excluding Goodwill)									$ 57
Collins Aerospace Systems [Member] | 10% Decrease in Excepted Future Cash Flows
Business Acquisition [Line Items]
Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount									3.00%
Collins Aerospace Systems [Member] | 50 Basis Points Decrease
Business Acquisition [Line Items]
Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount									7.00%
Collins Aerospace Systems [Member] | 50 Basis Points Increase
Business Acquisition [Line Items]
Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount									4.00%
Raytheon Company [Member]
Business Acquisition [Line Items]
Agreed Upon Number Shares of Common Stock of UTC which each share of Raytheon Common Stock will be Converted Into		2.3348
Fair value adjustments to fixed assets		$ 1,100
Fair value adjustment to future pension and postretirement benefit obligations		3,600
Customer Contractual Obligation		222
Goodwill, Acquired During Period		$ 21,600
Business Combination, Acquisition Related Costs									$ 17	$ 142
Blue Canyon [Member]
Business Acquisition [Line Items]
Goodwill, Acquired During Period					281
Payments to Acquire Businesses, Net of Cash Acquired					425
Finite-lived Intangible Assets Acquired					$ 149