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Nasdaq Stockholders' Equity (Common Stock in Treasury) (Details) - USD ($)
$ / shares in Units, $ in Millions
3 Months Ended
Mar. 31, 2017
Mar. 31, 2016
Equity [Abstract]    
Number of shares of common stock repurchased (in shares) 2,215,755 490,032
Average per share price of repurchased stock (in dollars per share) $ 70.64 $ 59.37
Total purchase price (in millions) $ 156 $ 29