Acquisitions and Divestitures - Summary of Estimated Fair Values of Assets Acquired and Liabilities Assumed at Acquisition Date (Detail) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Nov. 06, 2015
Business Acquisition [Line Items]
Goodwill	$ 10,807	$ 10,764	$ 10,695
Sikorsky Aircraft Corporation
Business Acquisition [Line Items]
Cash and cash equivalents				$ 75
Receivables, net				1,924
Inventories, net				1,632
Other current assets				46
Property, plant and equipment				649
Goodwill				2,842
Other noncurrent assets				572
Deferred income taxes, noncurrent				256
Total identifiable assets and goodwill				12,067
Accounts payable				(565)
Customer advances and amounts in excess of costs incurred				(1,197)
Salaries, benefits, and payroll taxes				(105)
Other current liabilities				(430)
Customer contractual obligations				(507)
Other noncurrent liabilities				(185)
Total liabilities assumed				(2,989)
Total consideration				9,078
Sikorsky Aircraft Corporation | Customer programs
Business Acquisition [Line Items]
Intangible assets				3,184
Sikorsky Aircraft Corporation | Trademarks
Business Acquisition [Line Items]
Intangible assets				$ 887