Postretirement Plans (Components Of Net Periodic Benefit Cost) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 2	$ 430	$ 402
Interest cost	2,925	2,781	2,991
Expected return on plan assets	(3,863)	(4,009)	(3,847)
Amortization of prior service credits	(79)	(56)	(39)
Recognized net actuarial loss/(gain)	643	1,130	804
Settlement/curtailment/other losses		44	1
Net periodic benefit (income)/cost	(372)	320	312
Other Postretirement Benefits Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	77	94	106
Interest cost	196	194	229
Expected return on plan assets	(8)	(8)	(7)
Amortization of prior service credits	(35)	(126)	(137)
Recognized net actuarial loss/(gain)	(46)	(10)	10
Net periodic benefit (income)/cost	184	144	201
Operating Income (Loss) [Member] | Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit (income)/cost included in (Loss)/earnings before income taxes	313	313	510
Operating Income (Loss) [Member] | Other Postretirement Benefits Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit (income)/cost included in (Loss)/earnings before income taxes	88	84	107
Other Income [Member] | Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit (income)/cost included in (Loss)/earnings before income taxes	(374)	(143)	(117)
Other Income [Member] | Other Postretirement Benefits Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit (income)/cost included in (Loss)/earnings before income taxes	107	101	123
Operating Income (Loss) Before Taxes [Member] | Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit (income)/cost included in (Loss)/earnings before income taxes	(61)	170	393
Operating Income (Loss) Before Taxes [Member] | Other Postretirement Benefits Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit (income)/cost included in (Loss)/earnings before income taxes	$ 195	$ 185	$ 230