Postretirement Plans (Net Periodic Benefit Cost) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 442	$ 415	$ 884	$ 829
Interest cost	747	758	1,494	1,542
Expected return on plan assets	(1,008)	(1,042)	(2,016)	(2,083)
Amortization of prior service costs	49	44	98	89
Recognized net actuarial loss	396	253	792	514
Settlement/curtailment/other losses/(gains)	73	(1)	111	337
Net periodic benefit cost	699	427	1,363	1,228
Net periodic benefit cost included in Earnings from operations	523	693	1,308	1,728
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	35	32	70	64
Interest cost	62	72	124	144
Expected return on plan assets	(2)	(2)	(4)	(4)
Amortization of prior service costs	(34)	(36)	(68)	(72)
Recognized net actuarial loss	11	$ 2	15	$ 4
Settlement/curtailment/other losses/(gains)	3		5
Net periodic benefit cost	75	$ 68	142	$ 136
Net periodic benefit cost included in Earnings from operations	$ 69	$ 72	$ 161	$ 143