Benefit Obligations (Schedule of Net Periodic Benefit Costs Recognized) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 3	$ 8	$ 6	$ 17
Interest cost	43	38	85	77
Expected return on plan assets	(54)	(56)	(108)	(112)
Amortization of prior service cost (credit)	0	1	0	1
Total	(8)	(9)	(17)	(17)
Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	1	1	2
Interest cost	0	3	2	5
Expected return on plan assets	0	0	0	0
Amortization of prior service cost (credit)	(22)	0	(41)	0
Total	$ (21)	$ 4	$ (38)	$ 7