Benefit Plans (Schedule of amounts recognized in Other comprehensive income) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, before Tax, [Abstract]
Amounts arising during the period	$ 422	$ (195)	$ (325)
Reclassification adjustment relating to prior service cost (credit)	(18)	(18)	(19)
Reclassification adjustment relating to actuarial (gain) loss	49	40	25
Total increase (decrease) in Other comprehensive income	$ 453	$ (173)	$ (319)