Earnings Per Common Share (Schedule Of The Computation Of Basic And Diluted Earnings Per Share) (Details) (USD $) In Millions, except Share data	3 Months Ended				9 Months Ended
	Sep. 30, 2011		Sep. 30, 2010		Sep. 30, 2011		Sep. 30, 2010
Earnings Per Share Basic And Diluted [Line Items]
Net income attributable to NASDAQ OMX	$ 110		$ 101		$ 306		$ 258
Accretion of series A convertible preferred stock							(1)
Net income attributable to common shareholders	$ 110		$ 101		$ 306		$ 257
Basic earnings per share	$ 0.62		$ 0.51		$ 1.73		$ 1.25
Diluted earnings per share	$ 0.61		$ 0.50		$ 1.70		$ 1.23
Weighted-average common shares outstanding for basic earnings per share	177,097,281	[1]	200,115,483	[1]	176,616,419	[1]	205,558,649	[1]
Weighted-average common shares outstanding for diluted earnings per share	180,924,442	[1]	204,072,891	[1]	180,317,010	[1]	209,204,611	[1]
Convertible Common Stock [Member]
Earnings Per Share Basic And Diluted [Line Items]
Weighted-average common shares outstanding for diluted earnings per share	34,482		34,482		34,482		34,482
Employee Equity Awards [Member]
Earnings Per Share Basic And Diluted [Line Items]
Weighted-average common shares outstanding for diluted earnings per share	3,792,679		3,922,926		3,666,109		3,611,480

[1] The decrease in the weighted-average common shares outstanding for basic and diluted earnings per share primarily reflects the weighted-average impact of the share repurchase from Borse Dubai and other purchases related to our share repurchase program completed in 2010. See "Share Repurchase Programs and Share Repurchase from Borse Dubai," of Note 12, "NASDAQ OMX Stockholders' Equity," for further discussion.