Postretirement Plans (Components Of Net Periodic Benefit Cost) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 604	$ 1,764	$ 1,661
Interest cost	3,050	2,990	3,058
Expected return on plan assets	(3,999)	(4,031)	(4,169)
Amortization of prior service costs/(credits)	38	196	177
Recognized net actuarial loss	790	1,577	1,020
Settlement/curtailment/other losses	40	290	461
Net periodic benefit cost	523	2,786	2,208
Net periodic benefit cost included in Earnings from operations	1,979	2,366	3,215
Other Postretirement Benefits Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	128	140	129
Interest cost	262	248	289
Expected return on plan assets	(8)	(8)	(8)
Amortization of prior service costs/(credits)	(126)	(136)	(144)
Recognized net actuarial loss	22	31	8
Settlement/curtailment/other losses		10	1
Net periodic benefit cost	278	285	275
Net periodic benefit cost included in Earnings from operations	$ 274	$ 288	$ 287