Goodwill And Purchased Intangible Assets (Schedule Of Changes In Goodwill) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011
Goodwill [Line Items]
Balance at December 31, 2010	$ 5,127
Goodwill acquired	20
Foreign currency translation adjustment	(86)
Balance at December 31, 2011	5,061
Market Services [Member]
Goodwill [Line Items]
Balance at December 31, 2010	4,679
Foreign currency translation adjustment	(77)
Balance at December 31, 2011	4,602
Issuer Services [Member]
Goodwill [Line Items]
Balance at December 31, 2010	292
Goodwill acquired	20
Foreign currency translation adjustment	(6)
Balance at December 31, 2011	306
Market Technology [Member]
Goodwill [Line Items]
Balance at December 31, 2010	156
Foreign currency translation adjustment	(3)
Balance at December 31, 2011	$ 153