Postretirement Plans (Net Periodic Benefit Cost) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 415	$ 473	$ 829	$ 946
Interest cost	758	731	1,542	1,462
Expected return on plan assets	(1,042)	(969)	(2,083)	(1,938)
Amortization of prior service costs	44	49	89	98
Recognized net actuarial loss	253	569	514	1,138
Settlement and curtailment loss	(1)		337	20
Net periodic benefit cost	427	853	1,228	1,726
Net periodic benefit cost included in Earnings from operations	693	753	1,728	1,544
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	32	37	64	74
Interest cost	72	66	144	133
Expected return on plan assets	(2)	(2)	(4)	(4)
Amortization of prior service costs	(36)	(45)	(72)	(90)
Recognized net actuarial loss	2	24	4	48
Net periodic benefit cost	68	80	136	161
Net periodic benefit cost included in Earnings from operations	$ 72	$ 88	$ 143	$ 179