Restructuring - Activities by Program (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance			$ 759
Expense	$ 186	$ 296	504	$ 642
(Payments) receipts, net			(632)
Non-cash activity			(153)
Restructuring reserve, ending balance	478		478
Separation Costs
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance			690
Expense	61	205	143	358
(Payments) receipts, net			(395)
Non-cash activity			0
Restructuring reserve, ending balance	438		438
Accelerated Depreciation
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance			0
Expense	66	41	192	173
(Payments) receipts, net			0
Non-cash activity			(192)
Restructuring reserve, ending balance	0		0
Other
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance			69
Expense	59	$ 50	169	$ 111
(Payments) receipts, net			(237)
Non-cash activity			39
Restructuring reserve, ending balance	$ 40		$ 40