| Document and Entity Information | Oct. 11, 2019 |
| Entity Listings [Line Items] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Oct. 11, 2019 |
| Entity Registrant Name | UNITED TECHNOLOGIES CORPORATION |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 001-00812 |
| 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 |
| Written Communications | true |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0000101829 |
| Common Stock [Member] | |
| Entity Listings [Line Items] | |
| Title of 12(b) Security | Common Stock ($1 par value) |
| Trading Symbol | UTX |
| Security Exchange Name | NYSE |
| 1.125% Notes due 2021 [Member] | |
| Entity Listings [Line Items] | |
| Title of 12(b) Security | 1.125% Notes due 2021 |
| Trading Symbol | UTX 21D |
| Security Exchange Name | NYSE |
| 1.250% Notes due 2023 [Member] | |
| Entity Listings [Line Items] | |
| Title of 12(b) Security | 1.250% Notes due 2023 |
| Trading Symbol | UTX 23 |
| Security Exchange Name | NYSE |
| 1.150% Notes due 2024 [Member] | |
| Entity Listings [Line Items] | |
| Title of 12(b) Security | 1.150% Notes due 2024 |
| Trading Symbol | UTX 24A |
| Security Exchange Name | NYSE |
| 1.875% Notes due 2026 [Member] | |
| Entity Listings [Line Items] | |
| Title of 12(b) Security | 1.875% Notes due 2026 |
| Trading Symbol | UTX 26 |
| Security Exchange Name | NYSE |
| 2.150% Notes due 2030 [Member] | |
| Entity Listings [Line Items] | |
| Title of 12(b) Security | 2.150% Notes due 2030 |
| Trading Symbol | UTX 30 |
| Security Exchange Name | NYSE |
| Floating Rate Notes due 2019 [Member] | |
| Entity Listings [Line Items] | |
| Title of 12(b) Security | Floating Rate Notes due 2019 |
| Trading Symbol | UTX 19C |
| Security Exchange Name | NYSE |
| Floating Rate Notes due 2020 [Member] | |
| Entity Listings [Line Items] | |
| Title of 12(b) Security | Floating Rate Notes due 2020 |
| Trading Symbol | UTX 20B |
| Security Exchange Name | NYSE |
