Segment and Related Information (Geographic Data) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues from external customers	$ 11,860	$ 12,286	$ 12,737
Long-lived assets	33,783	30,727
US [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues from external customers	9,457	9,950	11,084
Long-lived assets	22,638	20,776
UK [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues from external customers	2,403	2,336	1,653
Long-lived assets	$ 11,145	$ 9,951