Employee Benefit Plans (Status of Prepaid Benefits Costs and Accrued Benefit Liabilities Included in Other Assets and Other Liabilities) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Pension Plans, Defined Benefit [Member]
Change in Benefit Obligation
Benefit obligation at the beginning of the period	$ (11,113)	$ (9,198)
Acquisitions/Divestiture	0	(800)
Service cost	(243)	(218)	(178)
Interest cost	(474)	(486)	(469)
Plan participants' contributions	0	0
Medicare Part D subsidy receipts	0	0
Early retirement reinsurance program receipts	0	0
Amendments	62	72
Annuity purchase	1	0
Actuarial gains/(losses), net	(1,098)	(1,047)
Settlements	120	30
Curtailments	0	22
Special termination benefits	(8)	(4)
Benefits paid	599	612
Foreign currency changes and other	112	(96)
Benefit obligation at end of period	(12,042)	(11,113)	(9,198)
Change in plan assets
Fair value of plan assets at beginning of period	11,812	10,533
Actual Return on Plan Assets	1,097	1,616
Annuity purchase	(1)	0
Employer contributions	496	255
Plan participants' contributions	0	0
Early Retirement Reinsurance Program Receipts	0	0
Disbursements for settlements	(120)	(30)
Benefits paid	(599)	(612)
Acquisition/Divesture	0	53
Foreign currency changes and other	1	(3)
Fair value of plan assets at end of period	12,686	11,812	10,533
Funded status of plan at end of period	644	699
Amounts recognized in the Statement of Financial Position
Prepaid benefit cost	3,130	3,389
Accrued benefit liability	(2,486)	(2,690)
Net amount recognized	644	699
Items recorded in "Accumulated other comprehensive income' not year recognized as a component of net periodic (benefit) cost:
Transition obligation	0	0
Prior service cost	(81)	(9)
Net actuarial losst	2,548	1,815
Net amount not recognized	2,467	1,806
Accumulated benefit obligation	(11,502)	(10,616)
Other Postretirement Benefit Plans, Defined Benefit [Member]
Change in Benefit Obligation
Benefit obligation at the beginning of the period	(2,277)	(2,129)
Acquisitions/Divestiture	0	3
Service cost	(14)	(11)	(11)
Interest cost	(101)	(110)	(113)
Plan participants' contributions	(27)	(26)
Medicare Part D subsidy receipts	(18)	(11)
Early retirement reinsurance program receipts	0	(14)
Amendments	0	0
Annuity purchase	0	0
Actuarial gains/(losses), net	(134)	(184)
Settlements	0	0
Curtailments	0	0
Special termination benefits	0	0
Benefits paid	200	210
Foreign currency changes and other	(1)	(5)
Benefit obligation at end of period	(2,372)	(2,277)	(2,129)
Change in plan assets
Fair value of plan assets at beginning of period	1,344	1,495
Actual Return on Plan Assets	140	5
Annuity purchase	0	0
Employer contributions	18	14
Plan participants' contributions	27	26
Early Retirement Reinsurance Program Receipts	0	14
Disbursements for settlements	0	0
Benefits paid	(200)	(210)
Acquisition/Divesture	0	0
Foreign currency changes and other	0	0
Fair value of plan assets at end of period	1,329	1,344	1,495
Funded status of plan at end of period	(1,043)	(933)
Amounts recognized in the Statement of Financial Position
Prepaid benefit cost	0	0
Accrued benefit liability	(1,043)	(933)
Net amount recognized	(1,043)	(933)
Items recorded in "Accumulated other comprehensive income' not year recognized as a component of net periodic (benefit) cost:
Transition obligation	0	1
Prior service cost	(30)	(42)
Net actuarial losst	893	861
Net amount not recognized	863	820
Accumulated benefit obligation	$ (2,372)	$ (2,277)