Financial Instruments - Effect of Hedge Activity on Income and Expense (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Derivative Instruments, Gain (Loss)
Loss (income) from continuing operations before income taxes	$ (2,776)	$ (2,443)	$ (3,911)	$ (3,867)
Cost of Services
Derivative Instruments, Gain (Loss)
Loss (income) from continuing operations before income taxes	8,645		17,479
Gains/(losses) of total hedge activity	9		28
Cost of Sales
Derivative Instruments, Gain (Loss)
Loss (income) from continuing operations before income taxes	1,869		3,591
Gains/(losses) of total hedge activity	(6)		(23)
Cost of Financing
Derivative Instruments, Gain (Loss)
Loss (income) from continuing operations before income taxes	290		559
Gains/(losses) of total hedge activity	18		41
SG&A Expense
Derivative Instruments, Gain (Loss)
Loss (income) from continuing operations before income taxes	4,857		10,302
Gains/(losses) of total hedge activity	10		(23)
Other (Income) and Expense
Derivative Instruments, Gain (Loss)
Loss (income) from continuing operations before income taxes	280		692
Gains/(losses) of total hedge activity	(435)		(386)
Interest Expense
Derivative Instruments, Gain (Loss)
Loss (income) from continuing operations before income taxes	173		338
Gains/(losses) of total hedge activity	$ (17)		$ (33)