Postretirement Plans (Schedule Of Changes In The Benefit Obligation, Plan Assets And Funded Status Of Both Pensions And OPB) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position [Abstract]
Accrued pension plan liability, net	$ (14,408)	$ (16,276)
Pension Plans [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Beginning balance	77,645	71,424
Service cost	3	2	$ 430
Interest cost	2,455	2,925	2,781
Actuarial loss/(gain)	7,759	8,695
Settlement/curtailment/other	68	756
Gross benefits paid	(5,386)	(4,658)
Exchange rate adjustment	7	13
Ending balance	82,415	77,645	71,424
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Beginning balance at fair value	61,711	56,102
Actual return on plan assets	9,275	10,851
Company contribution	3,013	16
Settlement payments	(68)	(756)
Benefits paid	(5,241)	(4,514)
Exchange rate adjustment	6	12
Ending balance at fair value	68,696	61,711	56,102
Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position [Abstract]
Other assets	837	484
Accrued liabilities	(148)	(142)
Accrued pension plan liability, net	(14,408)	(16,276)
Net amount recognized	(13,719)	(15,934)
Other Postretirement Benefits Plans [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Beginning balance	5,080	5,114
Service cost	89	77	94
Interest cost	130	196	194
Amendments	(29)	1
Actuarial loss/(gain)	(218)	127
Settlement/curtailment/other	55
Gross benefits paid	(450)	(474)
Subsidies	36	36
Exchange rate adjustment		3
Ending balance	4,693	5,080	5,114
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Beginning balance at fair value	149	132
Actual return on plan assets	21	26
Company contribution		1
Plan participants' contributions	6	6
Benefits paid	(16)	(16)
Ending balance at fair value	160	149	$ 132
Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position [Abstract]
Accrued liabilities	(396)	(391)
Accrued retiree health care	(4,137)	(4,540)
Net amount recognized	$ (4,533)	$ (4,931)