Investments (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended			9 Months Ended											9 Months Ended
	Sep. 30, 2011		Sep. 30, 2010	Sep. 30, 2011		Sep. 30, 2010	Dec. 31, 2010		Sep. 30, 2011 Maximum [Member]	Sep. 30, 2011 Minimum [Member]	Sep. 30, 2011 Trading Securities [Member]	Dec. 31, 2010 Trading Securities [Member]	Sep. 30, 2011 Restricted Assets [Member]	Dec. 31, 2010 Restricted Assets [Member]	Sep. 30, 2011 Investment In Dubai Financial Market PJSC [Member]	Dec. 31, 2010 Investment In Dubai Financial Market PJSC [Member]	May 31, 2010 Investment In Dubai Financial Market PJSC [Member] NASDAQ Dubai [Member]	Sep. 30, 2011 EMCF [Member]	Dec. 31, 2010 EMCF [Member]
Schedule of Investments [Line Items]
Financial investments, at fair value	$ 294	[1]		$ 294	[1]		$ 253	[1]			$ 270	$ 220	$ 212	$ 190	$ 24	$ 33
Investment owned, percent of net assets																	1.00%
Trading securities cost															36	36
Unrealized holding loss in accumulated other comprehensive loss	(2)		7	(9)		2									(12)
Equity method investment, ownership percentage	22.00%			22.00%					50.00%	20.00%
Equity interest equity method investments																		27	27
Equity method investment, income (loss)	1		1	2		2
Deferred tax asset															5
Unrealized holding loss in accumulated other comprehensive loss															12
Valuation allowance															5
Income tax (benefit)	$ 61		$ 43	$ 151		$ 124									$ 0

[1] Primarily comprised of trading securities, mainly Swedish government debt securities, of $270 million as of September 30, 2011 and $220 million as of December 31, 2010. Of these securities, $212 million as of September 30, 2011 and $190 million as of December 31, 2010 are restricted assets to meet regulatory capital requirements primarily for NASDAQ OMX Stockholm's clearing operations. This balance also includes our 1% available-for-sale investment security in DFM of $24 million as of September 30, 2011 and $33 million as of December 31, 2010. See Note 6, "Investments," for further discussion of our trading investment securities and available-for-sale investment security.