Employee Benefit Plans (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Other Information	8.85%
Defined Benefit Plan, Estimated Future Employer Contributions in Next Fiscal Year	$ 675
Assumed Health care plan pre age	65
Assumed Health care plan post age	65
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Gains (Losses), before Tax	8,200	6,300
Pension and Other Postretirement Benefit Plans, Amounts that Will be Amortized from Accumulated Other Comprehensive Income (Loss) in Next Fiscal Year	220
Defined Benefit Plan, Description of Direction and Pattern of Change for Assumed Health Care Cost Trend Rate	0.05
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets	9.00%
actual rate of return	9.00%
Deferred Compensation Cash-based Arrangements, Liability, Current	372	264	313
United States Postretirement Benefit Plans of US Entity, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Other Costs	116	0	0
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Gains (Losses), before Tax	473	406
Special Termination Benefits [Member] | United States Postretirement Benefit Plans of US Entity, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Other Costs	$ 116