Retirement Benefits - Expense (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Effect of Change in Interest Method on Service and Interest Cost Components	$ (145)		$ (290)
U.S. Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	127	$ 146	255	$ 293
Interest cost	381	455	762	909
Expected return on assets	(674)	(732)	(1,347)	(1,464)
Amortization of prior service costs/(credits)	43	39	85	78
Net remeasurement (gain)/loss	0	0	0	0
Separation programs/other	3	0	3	2
Net periodic benefit cost/(income)	(120)	(92)	(242)	(182)
Non-U.S. Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	124	133	242	268
Interest cost	202	232	397	471
Expected return on assets	(350)	(369)	(689)	(744)
Amortization of prior service costs/(credits)	9	11	19	23
Net remeasurement (gain)/loss	11	0	11	0
Separation programs/other	65	12	72	19
Net periodic benefit cost/(income)	61	19	52	37
Worldwide OPEB
Defined Benefit Plan Disclosure [Line Items]
Service cost	12	15	24	30
Interest cost	49	59	97	119
Expected return on assets	0	0	0	0
Amortization of prior service costs/(credits)	(36)	(52)	(71)	(103)
Net remeasurement (gain)/loss	0	0	0	0
Separation programs/other	0	1	0	1
Net periodic benefit cost/(income)	25	$ 23	50	$ 47
Defined Benefit Plan, Estimated Future Employer Contributions To Funded Plans in Current Fiscal Year	1,500		1,500
Defined Benefit Plan Estimated Future Employer Discretionary Contributions In Next Fiscal Year			400
Pension And Other Postretirement Expected Benefit Contributions Unfunded Plans	300		300
Pension and Other Postretirement Benefit Contributions and Expected Future Employer Contributions To Funded and Unfunded Plans	$ 1,800		1,800
Pension and Other Postretirement Benefit Contributions			600
Pension and Other Postretirement Benefit Contributions Unfunded Plans			$ 150