Pensions and OPEB Obligations and Plan Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
US Pension Plans [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Beginning benefit obligation	$ 76,724	$ 71,480
Service Cost	272	247
Interest Cost	2,754	3,060	$ 2,837
Actuarial (gains) losses	(2,623)	7,770
Benefits paid	(5,641)	(5,779)
Foreign currency translation adjustments	0	0
Curtailments, settlements, and other	0	(54)
Ending benefit obligation	71,486	76,724	71,480
Defined Benefit Plan, Change in Plan Assets [Roll Forward]
Beginning fair value of plan assets	65,823	64,166
Actual return on plan assets	795	7,346
Employer contributions	95	143	128
Benefits paid	(5,641)	(5,779)
Foreign currency translation adjustments	0	0
Settlements and other	0	(53)
Ending fair value of plan assets	61,072	65,823	64,166
Ending funded status	(10,414)	(10,901)
Amounts recorded in the consolidated balance sheets [Abstract]
Non-current Assets	0	0
Current Liabilities	(67)	(69)
Non-current Liabilities	(10,347)	(10,832)
Net Amounts Recorded	(10,414)	(10,901)
Amounts recorded in Accumulated other comprehensive loss [Abstract]
Net actuarial gain (loss)	116	452
Net Prior Service (Cost) Credit	31	35
Total recorded in Accumulated other comprehensive income (loss)	147	487
Non-US Pension Plans [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Beginning benefit obligation	27,897	27,528
Service Cost	405	358
Interest Cost	763	1,031	1,010
Actuarial (gains) losses	(256)	3,179
Benefits paid	(1,332)	(1,699)
Foreign currency translation adjustments	(3,332)	(2,536)
Curtailments, settlements, and other	(382)	36
Ending benefit obligation	23,763	27,897	27,528
Defined Benefit Plan, Change in Plan Assets [Roll Forward]
Beginning fair value of plan assets	14,669	14,986
Actual return on plan assets	997	1,893
Employer contributions	1,120	770	886
Benefits paid	(1,332)	(1,699)
Foreign currency translation adjustments	(2,017)	(1,232)
Settlements and other	(447)	(49)
Ending fair value of plan assets	12,990	14,669	14,986
Ending funded status	(10,773)	(13,228)
Amounts recorded in the consolidated balance sheets [Abstract]
Non-current Assets	125	111
Current Liabilities	(334)	(383)
Non-current Liabilities	(10,564)	(12,956)
Net Amounts Recorded	(10,773)	(13,228)
Amounts recorded in Accumulated other comprehensive loss [Abstract]
Net actuarial gain (loss)	(3,796)	(5,019)
Net Prior Service (Cost) Credit	(33)	(57)
Total recorded in Accumulated other comprehensive income (loss)	(3,829)	(5,076)
Other Postretirement Benefit Plan [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Beginning benefit obligation	6,625	6,348
Service Cost	24	23	37
Interest Cost	238	273	274
Actuarial (gains) losses	(209)	448
Benefits paid	(407)	(426)
Foreign currency translation adjustments	(225)	(108)
Curtailments, settlements, and other	20	67
Ending benefit obligation	6,066	6,625	6,348
Defined Benefit Plan, Change in Plan Assets [Roll Forward]
Beginning fair value of plan assets	0	0
Actual return on plan assets	0	0
Employer contributions	385	402
Benefits paid	(407)	(426)
Foreign currency translation adjustments	0	0
Settlements and other	22	24
Ending fair value of plan assets	0	0	$ 0
Ending funded status	(6,066)	(6,625)
Amounts recorded in the consolidated balance sheets [Abstract]
Non-current Assets	0	0
Current Liabilities	(381)	(396)
Non-current Liabilities	(5,685)	(6,229)
Net Amounts Recorded	(6,066)	(6,625)
Amounts recorded in Accumulated other comprehensive loss [Abstract]
Net actuarial gain (loss)	(689)	(942)
Net Prior Service (Cost) Credit	63	88
Total recorded in Accumulated other comprehensive income (loss)	$ (626)	$ (854)