Pensions and Other Postretirement Benefits (Net Periodic Benefit Costs) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 15	$ 13
Interest cost	50	59
Expected return on plan assets	(70)	(74)
Amortization of actuarial losses	30	20
Amortization of prior service cost	(1)	0
Net periodic pension/other postretirement benefit cost	24	18
Other Postretirement Benefit Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	5	4
Interest cost	12	12
Expected return on plan assets	0	0
Amortization of actuarial losses	8	(2)
Amortization of prior service cost	(3)	4
Net periodic pension/other postretirement benefit cost	$ 22	$ 18