Organization And Nature Of Operations (Details) (USD $) In Billions, unless otherwise specified	9 Months Ended
	Sep. 30, 2011
Organization And Nature Of Operations [Abstract]
Operations in number of continents	6
Total number of U.S. listed companies	2,717
Home to listed companies with a combined market capitalization	$ 4,100
Total number of listed companies within Nordic and Baltic exchanges	771
Approximate combined market capitalization	$ 814