New Accounting Standards - Effect of change related to ASU 2017-07 (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cost of sales	$ 33,349	$ 32,522	$ 66,057	$ 63,039
Selling, administrative, and other expenses	2,756	2,784	5,520	5,474
Accounting Standards Update 2017-07 [Member] | Scenario, Previously Reported [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cost of sales		32,348		62,629
Selling, administrative, and other expenses		2,661		5,223
Accounting Standards Update 2017-07 [Member] | Scenario, Adjustment [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cost of sales		174		410
Selling, administrative, and other expenses		123		251
Operating Segments [Member] | Non-Financial Services
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other income/(loss), net	$ 658	686	$ 1,370	1,454
Operating Segments [Member] | Non-Financial Services | Accounting Standards Update 2017-07 [Member] | Scenario, Previously Reported [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other income/(loss), net		389		793
Operating Segments [Member] | Non-Financial Services | Accounting Standards Update 2017-07 [Member] | Scenario, Adjustment [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other income/(loss), net		$ 297		$ 661