Benefit Plans (Postretirement Health Costs) (Details) (Postretirement Benefit Plan [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Postretirement Benefit Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 18	$ 18	$ 34
Interest cost	99	115	139
Amortization of net loss	51	40	39
Amortization of Prior service cost	(45)	(45)	(21)
Termination and curtailment	0	(26)	(4)
Net periodic benefit costs	$ 123	$ 102	$ 187