Earnings Per Common Share (Schedule Of The Computation Of Basic And Diluted Earnings Per Share) (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Earnings Per Share Basic And Diluted [Line Items]
Net income attributable to NASDAQ OMX	$ 387		$ 395		$ 266
Accretion of series A convertible preferred stock			(1)
Net income attributable to common shareholders for basic earnings per share	387		394		266
Interest impact of 3.75% convertible notes, net of tax					2
Net income attributable to common shareholders for diluted earnings per share	$ 387		$ 394		$ 268
Weighted-average common shares outstanding for basic earnings per share	176,331,819	[1]	202,975,623	[1]	204,698,277	[1]
3.75% convertible notes assumed converted into common stock	34,482		34,482		6,066,985
Weighted-average common shares outstanding for diluted earnings per share	180,011,247	[1]	206,514,655	[1]	214,537,907	[1]
Basic earnings per share	$ 2.20		$ 1.94		$ 1.30
Diluted earnings per share	$ 2.15		$ 1.91		$ 1.25
Employee Equity Awards [Member]
Earnings Per Share Basic And Diluted [Line Items]
Employee equity awards	3,644,946		3,504,550		3,772,645

[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 programs completed in 2011 and 2010. See "Share Repurchase Programs and Share Repurchase from Borse Dubai," of Note 12, "NASDAQ OMX Stockholders' Equity," for further discussion.