Postretirement Plans (Net Periodic Benefit Cost) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 415	$ 468	$ 1,244	$ 1,414
Interest cost	758	713	2,300	2,175
Expected return on plan assets	(1,042)	(969)	(3,125)	(2,907)
Amortization of prior service costs	44	52	133	150
Recognized net actuarial loss	254	530	768	1,668
Settlement and curtailment loss	35	84	372	104
Net periodic benefit cost	464	878	1,692	2,604
Net periodic benefit cost included in Earnings from operations	715	775	2,443	2,319
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	33	37	97	111
Interest cost	72	65	216	198
Expected return on plan assets	(2)	(1)	(6)	(5)
Amortization of prior service costs	(36)	(45)	(108)	(135)
Recognized net actuarial loss	2	24	6	72
Net periodic benefit cost	69	80	205	241
Net periodic benefit cost included in Earnings from operations	$ 71	$ 90	$ 214	$ 269