Employee Postretirement Benefits (Benefit Cost Information For Defined Benefit Plans And Other Postretirement Benefit Plans) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Defined Benefit Plans [Member]
Service cost	$ 12	$ 14	$ 24	$ 28
Interest cost	70	78	140	154
Expected return on plan assets	(82)	(87)	(165)	(173)
Recognized net actuarial loss	28	23	55	47
Other	6	2	17	2
Net periodic benefit cost	34	30	71	58
Other Postretirement Benefit Plans [Member]
Service cost	4	3	8	7
Interest cost	10	11	19	22
Expected return on plan assets	0	0	0	0
Recognized net actuarial loss	0	0	0	0
Other	(1)	1	(1)	2
Net periodic benefit cost	$ 13	$ 15	$ 26	$ 31