NASDAQ OMX Stockholders' Equity (Narrative) (Details) (USD $)	9 Months Ended						12 Months Ended		9 Months Ended					12 Months Ended
	Sep. 30, 2010	Oct. 12, 2011	Sep. 30, 2011	Dec. 31, 2010	Sep. 30, 2011 Series A Preferred Stock [Member]	Dec. 31, 2010 Series A Preferred Stock [Member]	Dec. 31, 2010 Share Repurchase Program [Member]	Dec. 31, 2010 Share Repurchase Program [Member] Borse Dubai [Member]	Sep. 30, 2011 Other Repurchases Of Common Stock [Member]	Sep. 30, 2011 Investor AB [Member]	Feb. 28, 2011 Investor AB [Member]	Dec. 31, 2010 Investor AB [Member]	Dec. 31, 2010 S L P [Member]	Dec. 31, 2010 Borse Dubai [Member]	Sep. 30, 2011 Borse Dubai [Member]	Dec. 31, 2008 Borse Dubai [Member]
Stockholders Equity [Line Items]
Common stock, shares authorized			300,000,000	300,000,000
Common stock, shares issued			213,381,697	213,370,086												60,561,515
Common stock, shares outstanding			177,136,116	175,782,683						18,954,142	1,000,000	8,000,000			29,780,515
Common stock in treasury, shares			36,245,581	37,587,403
Common stock holder voting rights			5.00%
Board of Directors authorized share repurchase program		$ 300,000,000					$ 550,000,000
Number of shares approved for repurchase by the Board of Directors								22,781,000
Cash paid for repurchase of common stock	300,000,000						300,000,000
Treasury shares acquired							15,050,647		105,596					22,781,000
Common stock outstanding												17,004,142	10,539,614
Average price of repurchased stock							$ 19.95	$ 21.82
Preferred stock, shares authorized			30,000,000	30,000,000
Preferred stock par value			$ 0.01
Preferred stock, series A convertible preferred stock: shares issued			1,600,000	1,600,000	1,600,000	1,600,000
Preferred stock, series A convertible preferred stock: shares outstanding			0	0	0	0
Aggregate purchase price			$ 769,000,000	$ 796,000,000				$ 497,000,000