Pension and Other Postretirement Benefits (Change in Benefit Obligation) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Pension And Other Postretirement Benefits Details [Abstract]
Service period over which benefits vest	5Y
Percent of plan assets' fair value invested in Company common stock	1.30%	1.00%
Pension Benefits [Member]
Defined Change in Benefit Obligation [Roll Forward]
Benefit obligation, beginning of year	5,191	4,974
Service cost	36	34
Interest cost	243	249
Actuarial loss (gain)	498	366
Benefits paid	(413)	(427)
Participants' contributions	0	0
Retiree Medicare drug subsidy	0	0
Early retirement reimbursement program	0	0
Cumulative translation adjustments	9	(5)
Benefit obligation, end of year	5,564	5,191
Postretirement Benefits [Member]
Defined Change in Benefit Obligation [Roll Forward]
Benefit obligation, beginning of year	697	785
Service cost	0	0
Interest cost	33	38
Actuarial loss (gain)	1	(67)
Benefits paid	(78)	(80)
Participants' contributions	11	12
Retiree Medicare drug subsidy	12	7
Early retirement reimbursement program	0	2
Cumulative translation adjustments	0	0
Benefit obligation, end of year	676	697