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		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Defined Benefit Plans [Member]
Service cost	$ 10	$ 14	$ 34	$ 42
Interest cost	69	77	209	231
Expected return on plan assets	(82)	(87)	(247)	(260)
Recognized net actuarial loss	27	23	82	70
Other	3	4	20	6
Net periodic benefit cost	27	31	98	89
Other Postretirement Benefit Plans [Member]
Service cost	3	3	11	10
Interest cost	9	10	28	32
Expected return on plan assets	0	0	0	0
Recognized net actuarial loss	0	0	0	0
Other	1	0	0	2
Net periodic benefit cost	$ 13	$ 13	$ 39	$ 44