Postretirement Plans (Components Of Net Periodic Benefit Cost) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 430	$ 402	$ 604
Interest cost	2,781	2,991	3,050
Expected return on plan assets	(4,009)	(3,847)	(3,999)
Amortization of prior service (credits)/costs	(56)	(39)	38
Recognized net actuarial loss	1,130	804	790
Settlement/curtailment/other losses	44	1	40
Net periodic benefit cost	320	312	523
Other Postretirement Benefits Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	94	106	128
Interest cost	194	229	262
Expected return on plan assets	(8)	(7)	(8)
Amortization of prior service (credits)/costs	(126)	(137)	(126)
Recognized net actuarial loss	(10)	10	22
Settlement/curtailment/other losses
Net periodic benefit cost	144	201	278
Operating Income (Loss) [Member] | Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost included in Earnings before income taxes	313	510	1,257
Operating Income (Loss) [Member] | Other Postretirement Benefits Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost included in Earnings before income taxes	84	107	144
Other Income [Member] | Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost included in Earnings before income taxes	(143)	(117)	327
Other Income [Member] | Other Postretirement Benefits Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost included in Earnings before income taxes	101	123	151
Operating Income (Loss) Before Taxes [Member] | Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost included in Earnings before income taxes	170	393	1,584
Operating Income (Loss) Before Taxes [Member] | Other Postretirement Benefits Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost included in Earnings before income taxes	$ 185	$ 230	$ 295