Business Segments (Schedule Of Operating Segments) (Details) (USD $) In Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2011		Sep. 30, 2010	Sep. 30, 2011		Sep. 30, 2010
Segment Reporting Information [Line Items]
Total revenues	$ 946		$ 757	$ 2,601		$ 2,414
Cost of revenues	(508)		(385)	(1,332)		(1,293)
Revenues less transaction rebates, brokerage, clearance and exchange fees	438		372	1,269		1,121
Income (loss) before income taxes	170	[1]	143	453	[1]	378	[2]
Loss on divestiture of businesses						11
Repayments of secured debt				6		37
Senior Secured Credit Facilities [Member]
Segment Reporting Information [Line Items]
Repayments of secured debt						40
Market Services [Member]
Segment Reporting Information [Line Items]
Total revenues	808		634	2,190		2,052
Cost of revenues	(508)		(385)	(1,332)		(1,293)
Revenues less transaction rebates, brokerage, clearance and exchange fees	300		249	858		759
Income (loss) before income taxes	146	[1]	111	393	[1]	335	[2]
Issuer Services [Member]
Segment Reporting Information [Line Items]
Total revenues	92		85	276		255
Cost of revenues
Revenues less transaction rebates, brokerage, clearance and exchange fees	92		85	276		255
Income (loss) before income taxes	28	[1]	30	90	[1]	90	[2]
Market Technology [Member]
Segment Reporting Information [Line Items]
Total revenues	46		38	135		106
Cost of revenues
Revenues less transaction rebates, brokerage, clearance and exchange fees	46		38	135		106
Income (loss) before income taxes	4	[1]	1	10	[1]	5	[2]
Corporate Items And Eliminations [Member]
Segment Reporting Information [Line Items]
Total revenues						1
Cost of revenues
Revenues less transaction rebates, brokerage, clearance and exchange fees						1
Income (loss) before income taxes	(8)	[1]	1	(40)	[1]	(52)	[2]
NEURO [Member]
Segment Reporting Information [Line Items]
Loss on divestiture of businesses						6
Agora-X [Member]
Segment Reporting Information [Line Items]
Loss on divestiture of businesses						$ 5

[1] Corporate items and eliminations for the three and nine months ended September 30, 2011 primarily include merger and strategic initiatives expense as well as costs incurred in connection with the termination of our 2010 Credit Facility. See "2010 Credit Facility," of Note 8, "Debt Obligations," for further discussion.

[2] Corporate items and eliminations for the nine months ended September 30, 2010 primarily include charges of $40 million related to the repayment of our senior secured credit facilities in place as of December 31, 2009 and $11 million related to loss on divestiture of businesses as a result of our decision to close the businesses of both NASDAQ OMX Europe, or NEURO, ($6 million) and Agora-X LLC, or Agora-X, ($5 million).