Acquisitions, Dispositions, Goodwill and Other Intangible Assets (General Information) (Details) $ in Millions	6 Months Ended
Jun. 30, 2017 USD ($)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Acquisition Cost Of Acquired Entities and Interest in Affiliates	$ 168

The total cost of acquired entities and interest in affiliates including the cash paid to shareholders, fair value of debt and equity securities issued to shareholders, the fair value of the liabilities assumed, and direct costs of the acquisitions and interest in affiliates.

No definition available.

Name:	utx_AcquisitionCostOfAcquiredEntitiesAndInterestInAffiliates
Namespace Prefix:	utx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration