Summary of Significant Accounting Policies (Components of Fixed Assets and Capitalized Software Costs) (Details) (USD $) In Millions, unless otherwise specified										12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 Furniture and Fixtures [Member]	Dec. 31, 2012 Furniture and Fixtures [Member]	Dec. 31, 2013 Land and Building [Member]	Dec. 31, 2012 Land and Building [Member]	Dec. 31, 2013 Leasehold Improvements [Member]	Dec. 31, 2012 Leasehold Improvements [Member]	Dec. 31, 2013 Minimum [Member] Software Development [Member]	Dec. 31, 2013 Minimum [Member] Furniture and Fixtures [Member]	Dec. 31, 2013 Minimum [Member] Building [Member]	Dec. 31, 2013 Maximum [Member] Software Development [Member]	Dec. 31, 2013 Maximum [Member] Furniture and Fixtures [Member]	Dec. 31, 2013 Maximum [Member] Building [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 2,425	$ 2,391		$ 1,201	$ 1,168	$ 408	$ 412	$ 816	$ 811
Less-accumulated depreciation and amortization	(1,597)	(1,582)
Property, plant and equipment, net	828	809	804
Property, plant and equipment, useful life										3 years	3 years	30 years	10 years	10 years	40 years
Capitalized computer software costs	399	278
Capitalized computer software costs accumulated amortization	$ 748	$ 691