Property, plant and equipment and assets held for lease - Narrative (Detail) - Insurance and Other [Member] - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Property, plant and equipment, net	$ 23,807	$ 20,104
Property, plant and equipment, gross	43,471	37,424
Property, plant and equipment, accumulated depreciation	19,664	17,320
Machinery and equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	27,707	$ 21,935
ASC 606 [Member] | Aircraft Sold Under Fractional Aircraft Ownership Programs [Member]
Property, Plant and Equipment [Line Items]
Other liabilities for estimated repurchase obligations and unearned lease revenues	3,500
ASC 606 [Member] | Machinery and equipment [Member] | Aircraft Sold Under Fractional Aircraft Ownership Programs [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, net	3,500
Property, plant and equipment, gross	5,300
Property, plant and equipment, accumulated depreciation	$ 1,800