Acquisitions, Dispositions, Goodwill and Other Intangible Assets (General Information) (Details) - USD ($)	3 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2018	Sep. 30, 2017	Sep. 04, 2017
Business Acquisition [Line Items]
Acquisition Cost Of Acquired Entities and Interest in Affiliates		$ 177,000,000
Gain on sale of Taylor Company		799,000,000	$ 0
Proceeds from Issuance of Debt		11,000,000,000
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		591,000,000
Proceeds from Debt, Net of Issuance Costs		10,900,000,000
Restricted Cash	$ 9,245,000,000	9,245,000,000	$ 33,000,000
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
Proceeds from Issuance of Debt	9,200,000,000
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