Acquisitions, Dispositions, Goodwill and Other Intangible Assets (General Information) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2018	Sep. 04, 2017
Business Acquisition [Line Items]
Acquisition Cost Of Acquired Entities and Interest in Affiliates	$ 125,000,000
Unsecured bridge loan credit agreement		$ 6,500,000,000
Rockwell Collins [Member]
Business Acquisition [Line Items]
Business Acquisition, Date of Acquisition Agreement	Sep. 04, 2017
Business Acquisition, Name of Acquired Entity	Rockwell Collins, Inc. (Rockwell Collins)
Business Acquisition Cash Paid Per Share	$ 93.33
Business Acquisition UTC stock payable	46.67
Payments to Acquire Businesses, Gross	15,000,000,000
Unsecured bridge loan credit agreement	6,500,000,000
Business Acquisition, Assumed Long-term Debt	$ 7,000,000,000