Stockholders' Equity Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Accumulated Other Comprehensive Loss, Net of Tax [Roll Forward]
Balance at beginning of period			$ 44,075	$ 40,323
Other comprehensive income (loss), net of tax	$ (118)	$ 152	(39)	114
Balance at end of period	45,725	44,003	45,725	44,003
Foreign currency translation adjustments [Member]
Accumulated Other Comprehensive Loss, Net of Tax [Roll Forward]
Balance at beginning of period	(2,264)	(1,949)	(2,355)	(2,034)
Other comprehensive income net of reclassification adjustment, noncontrolling interests and tax	102	(10)	193	75
Balance at end of period	(2,162)	(1,959)	(2,162)	(1,959)
Defined benefit plans [Member]
Accumulated Other Comprehensive Loss, Net of Tax [Roll Forward]
Balance at beginning of period	(6,997)	(6,121)	(6,968)	(5,999)
Other comprehensive income (loss) before reclassification adjustment, net of tax	(266)	133	(343)	(15)
Reclassification adjustment, net of tax	55	38	103	64
Other comprehensive income (loss), net of tax	(211)	171	(240)	49
Balance at end of period	$ (7,208)	$ (5,950)	$ (7,208)	$ (5,950)