Employee Benefit Plans (Components of Net Periodic Benefit Cost Included in General and Administrative Expenses) (Details) and (Parenthetical 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
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 61	$ 58	$ 182	$ 163
Interest cost	117	123	355	365
Expected return on plan assets	(181)	(180)	(543)	(539)
Amortization of prior service cost	4	6	10	18
Amortization of actuarial (gain) loss, net	27	10	80	30
Curtailments	0	0	0	0
Special Termination Benefits	5	1	7	3
Net periodic (benefit) cost	33	18	91	40
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	4	3	11	9
Interest cost	25	27	76	81
Expected return on plan assets	(22)	(24)	(66)	(72)
Amortization of prior service cost	(3)	(3)	(9)	(9)
Amortization of actuarial (gain) loss, net	14	9	41	27
Curtailments	0	0	0	0
Special Termination Benefits	0	0	0	0
Net periodic (benefit) cost	$ 18	$ 12	$ 53	$ 36