Changes in Accumulated Other Comprehensive Losses (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	$ 144,914	$ 156,118	$ 145,208	$ 155,642
Components of Other Comprehensive Income (Loss):
Before Reclassifications			(7)	(1)
Reclassifications			247	188
Other Comprehensive Gain (Loss), Net of Tax	134	102	240	187
Ending balance	134,386	157,451	134,386	157,451
Related income taxes	(2,320)	1,645	(1,756)	2,960
Total
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(4,884)	(3,459)	(4,990)	(3,544)
Components of Other Comprehensive Income (Loss):
Other Comprehensive Gain (Loss), Net of Tax	134	102	240	187
Ending balance	(4,750)	(3,357)	(4,750)	(3,357)
Currency Translation Adjustment
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance			(142)	(124)
Components of Other Comprehensive Income (Loss):
Before Reclassifications			(12)	1
Reclassifications			0	0
Other Comprehensive Gain (Loss), Net of Tax			(12)	1
Ending balance	(154)	(123)	(154)	(123)
Unrealized Holding Gains (Losses) on Securities
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance			(8)	(10)
Components of Other Comprehensive Income (Loss):
Before Reclassifications			(4)	0
Reclassifications			0	0
Other Comprehensive Gain (Loss), Net of Tax			(4)	0
Ending balance	(12)	(10)	(12)	(10)
Derivatives
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance			0	(2)
Components of Other Comprehensive Income (Loss):
Before Reclassifications			0	(1)
Reclassifications			0	0
Other Comprehensive Gain (Loss), Net of Tax			0	(1)
Ending balance	0	(3)	0	(3)
Defined Benefit Plans
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance			(4,840)	(3,408)
Components of Other Comprehensive Income (Loss):
Before Reclassifications			9	(1)
Reclassifications			247	188
Other Comprehensive Gain (Loss), Net of Tax			256	187
Ending balance	$ (4,584)	$ (3,221)	(4,584)	$ (3,221)
Defined Benefit Plans | Reclassification out of Accumulated Other Comprehensive Income
Components of Other Comprehensive Income (Loss):
Employee Benefits for reclassified components			327
Related income taxes			$ 80