Benefit Obligations (Schedule of Net Periodic Benefit Costs Recognized) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 3	$ 9
Interest cost	42	39
Expected return on plan assets	(54)	(56)
Amortization of prior service cost (credit)	0	0
Total	(9)	(8)
Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	1
Interest cost	2	2
Expected return on plan assets	0	0
Amortization of prior service cost (credit)	(19)	0
Total	$ (17)	$ 3