Pensions and Other Postretirement Benefits (Net Periodic Benefit Costs) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Defined Contribution Pension [Member] | Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 14	$ 13	$ 29	$ 28
Interest cost	54	56	106	112
Expected return on plan assets	(75)	(67)	(139)	(134)
Amortization of actuarial losses	32	34	60	66
Settlement losses (Canada)	0	0	18	0
Net periodic pension/other postretirement benefit cost	25	36	74	72
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	5	4	10	9
Interest cost	13	12	25	26
Amortization of prior service cost	(3)	(3)	(5)	(4)
Amortization of actuarial losses	7	6	14	15
Net periodic pension/other postretirement benefit cost	$ 22	$ 19	$ 44	$ 46