Employee Benefit Plans (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service Cost	$ 0	$ 0
Interest Cost	215	232
Expected Return on Plan Assets	(184)	(176)
Amortization of Prior Service Benefit	0	0
Recognized net actuarial loss (gain)	56	36
Settlements	6	0
Net periodic cost	93	92
Other Postretirement and Postemployment Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service Cost	12	15
Interest Cost	36	41
Expected Return on Plan Assets	(21)	(19)
Amortization of Prior Service Benefit	(7)	(3)
Recognized net actuarial loss (gain)	6	6
Settlements	0	0
Net periodic cost	$ 26	$ 40