Income Taxes (Schedule of Unrecognized Tax Benefits Roll Forward) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits – January 1	$ 1,055	$ 939	$ 1,198
Gross increases – tax positions in prior periods	10	55	154
Gross decreases – tax positions in prior periods	(125)	(20)	(383)
Gross increases – current-period tax positions	202	83	28
Gross decreases – current-period tax positions	(1)	(1)	(15)
Settlements		(1)	(42)
Lapse of statute of limitations			(1)
Unrecognized tax benefits – December 31	$ 1,141	$ 1,055	$ 939