Document and Entity Information	9 Months Ended
	Sep. 30, 2019 shares
Amendment Flag	false
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--12-31
Entity Registrant Name	UNITED TECHNOLOGIES CORP /DE/
Entity Central Index Key	0000101829
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2019
Document Transition Report	false
Entity File Number	1-812
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	06-0570975
Entity Address, Address Line One	10 Farm Springs Road,
Entity Address, City or Town	Farmington,
Entity Address, State or Province	CT
Entity Address, Postal Zip Code	06032
City Area Code	(860)
Local Phone Number	728-7000
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding	863,268,940
Common Stock [Member]
Title of 12(b) Security	Common Stock ($1 par value)
Trading Symbol	UTX
Security Exchange Name	NYSE
Note 1.125% Due 2021 [Member]
Title of 12(b) Security	1.125% Notes due 2021
Trading Symbol	UTX 21D
Security Exchange Name	NYSE
Notes 1.250% due 2023 [Member]
Title of 12(b) Security	1.250% Notes due 2023
Trading Symbol	UTX 23
Security Exchange Name	NYSE
Notes 1.150% Due 2024 [Member]
Title of 12(b) Security	1.150% Notes due 2024
Trading Symbol	UTX 24A
Security Exchange Name	NYSE
Notes 1.875% Due 2026 [Member]
Title of 12(b) Security	1.875% Notes due 2026
Trading Symbol	UTX 26
Security Exchange Name	NYSE
Notes 2.150% Due 2030 [Member]
Title of 12(b) Security	2.150% Notes due 2030
Trading Symbol	UTX 30
Security Exchange Name	NYSE
Floating Rate Notes Due2019 [Member]
Title of 12(b) Security	Floating Rate Notes due 2019
Trading Symbol	UTX 19C
Security Exchange Name	NYSE
Floating Rate Notes Due2020 [Member]
Title of 12(b) Security	Floating Rate Notes due 2020
Trading Symbol	UTX 20B
Security Exchange Name	NYSE