Acquisitions, Dispositions, Goodwill and Other Intangible Assets (General Information) (Details) - USD ($) shares in Millions	3 Months Ended	6 Months Ended		12 Months Ended
	Jun. 30, 2019	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018	Nov. 26, 2018
Business Acquisition [Line Items]
Acquisition Cost Of Acquired Entities and Interest in Affiliates		$ 32,000,000
Proceeds from Issuance of Debt				$ 11,000,000,000.0
Proceeds from Debt, Net of Issuance Costs				$ 10,900,000,000
Goodwill Resulting from Business Combinations		263,000,000
Contractual Obligation, Due in Next Fiscal Year	$ 77,000,000	77,000,000
Contractual Obligation, Due in Second Year	129,000,000	129,000,000
Contractual Obligation, Due in Third Year	131,000,000	131,000,000
Contractual Obligation, Due in Fourth Year	132,000,000	132,000,000
Contractual Obligation, Due in Fifth Year	$ 119,000,000	119,000,000
Business Combination, Acquisition Related Costs		$ 10,000,000	$ 50,000,000
Raytheon Company [Member]
Business Acquisition [Line Items]
Business Acquisition, Date of Acquisition Agreement	Jun. 09, 2019
Business Acquisition, Name of Acquired Entity	Raytheon Company
Business Acquisition UTC stock payable	$ 2.3348
Rockwell Collins [Member]
Business Acquisition [Line Items]
Business Acquisition, Effective Date of Acquisition				Nov. 26, 2018
Business Acquisition, Name of Acquired Entity				Rockwell Collins
Business Acquisition Cash Paid Per Share				$ 93.33
Business Acquisition UTC stock payable				0.37525
Payments to Acquire Businesses, Gross				15,533,000,000
Payments to Acquire Businesses, Net of Cash Acquired				$ 14,900,000,000
Stock Issued During Period, Shares, Acquisitions				62.2
Noncash or Part Noncash Acquisition, Debt Assumed				$ 7,800,000,000
Noncash or Part Noncash Acquisition, Value of Assets Acquired				30,600,000,000
Stock Issued During Period, Value, Acquisitions				7,960,000,000
Business Combination, Consideration Transferred				23,493,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents					$ 640,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables					1,665,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Inventory					1,511,000,000
Business combination, recognized identifiable assets acquired and liabilities assumed, contract with customer asset, current					289,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Other					263,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Assets Noncurrent					37,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment					1,673,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Indefinite-Lived Intangible Assets					1,870,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets					210,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets					16,978,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Long-term Debt					2,254,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Accounts Payable					515,000,000
Business combination, recognized identifiable assets acquired and liabilities assumed, accrued liabilities current					1,618,000,000
Business combination, recognized identifiable assets acquired and liabilities assumed, contract with customer liabilities, current					301,000,000
Business Acquisition, Assumed Long-term Debt					5,530,000,000
Business combination, recognized identifiable assets acquired and liabilities assumed, liability, defined benefit plan, noncurrent					502,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Other					3,481,000,000
Business combination, recognized identifiable assets acquired and liabilities assumed, noncontrolling interest					6,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities					14,207,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net					2,771,000,000
Goodwill Resulting from Business Combinations				$ 20,722,000,000
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net					23,493,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill					10,690,000,000
Fair value adjustment, inventory					282,000,000
Fair value adjustment, fixed assets					269,000,000
Contractual Obligation					1,020,000,000
Rockwell Collins [Member] | Customer Relationships [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles					8,220,000,000
Rockwell Collins [Member] | Customer Relationships [Member] | Maximum [Member]
Business Acquisition [Line Items]
Finite-Lived Intangible Asset, Useful Life		20 years
Rockwell Collins [Member] | Customer Relationships [Member] | Minimum [Member]
Business Acquisition [Line Items]
Finite-Lived Intangible Asset, Useful Life		10 years
Rockwell Collins [Member] | Technology-Based Intangible Assets [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles					$ 600,000,000
Finite-Lived Intangible Asset, Useful Life		15 years