Benefit Plans (Funded Status) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation at January 1	$ 3,003	$ 2,798
Service cost	12	13	16
Interest cost	135	146	149
Participants' contributions
Plan amendments
Actuarial (gain) loss	266	263
Benefits paid	(164)	(163)
Foreign currency translation and other on benefit obligation	19
Reduction of benefit obligations due to disposition of subsidiary		(54)
Benefit obligation at December 31	3,271	3,003	2,798
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at January 1	2,212	2,258
Actual return on plan assets	245	82
Company contributions	115	89
Participants' contributions
Benefits paid	(164)	(163)
Foreign currency translation and other on plan assets	17
Reduction of plan assets due to disposition of subsidiary		(54)
Fair value of plan assets at December 31	2,425	2,212	2,258
Defined Benefit Plan, Funded Status of Plan [Abstract]
Funded status	(846)	(791)
Defined Benefit Plan, Amounts Recognized in Balance Sheet [Abstract]
Other assets		1
Other liabilities	(846)	(792)
Net amount recognized on balance sheets	(846)	(791)
Amounts recognized in Accumulated other comprehensive income not yet recognized in net periodic cost (benefit)[Abstract]
Prior service credit
Net actuarial (gain) loss	1,213	1,060
Net amount recognized in Accumulated other comprehensive income	1,213	1,060
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation at January 1	49	95
Service cost		1	1
Interest cost	2	3	7
Participants' contributions	5	6
Plan amendments		(12)
Actuarial (gain) loss	3	(18)
Benefits paid	(12)	(13)
Foreign currency translation and other on benefit obligation
Reduction of benefit obligations due to disposition of subsidiary		(13)
Benefit obligation at December 31	47	49	95
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at January 1
Actual return on plan assets
Company contributions	7	7
Participants' contributions	5	6
Benefits paid	(12)	(13)
Foreign currency translation and other on plan assets
Reduction of plan assets due to disposition of subsidiary
Fair value of plan assets at December 31
Defined Benefit Plan, Funded Status of Plan [Abstract]
Funded status	(47)	(49)
Defined Benefit Plan, Amounts Recognized in Balance Sheet [Abstract]
Other assets
Other liabilities	(47)	(49)
Net amount recognized on balance sheets	(47)	(49)
Amounts recognized in Accumulated other comprehensive income not yet recognized in net periodic cost (benefit)[Abstract]
Prior service credit	(116)	(134)
Net actuarial (gain) loss	11	9
Net amount recognized in Accumulated other comprehensive income	$ (105)	$ (125)