Acquisitions, Dispositions, Goodwill and Other Intangible Assets (General Information) (Details) - USD ($)	3 Months Ended	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2018	Jun. 30, 2017	Sep. 04, 2017
Business Acquisition [Line Items]
Acquisition Cost Of Acquired Entities and Interest in Affiliates		$ 134,000,000
Gain on sale of Taylor Company		795,000,000	$ 0
Unsecured bridge loan credit agreement				$ 6,500,000,000
Proceeds from sale of Taylor Company		1,000,000,000
After tax gain on sale of Taylor Company		588,000,000
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	6,500,000,000
Business Acquisition, Assumed Long-term Debt	$ 7,000,000,000	$ 7,000,000,000