Goodwill and Other Intangibles (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended			12 Months Ended				1 Months Ended	3 Months Ended	12 Months Ended		12 Months Ended		1 Months Ended	12 Months Ended				3 Months Ended	12 Months Ended	1 Months Ended	12 Months Ended
	Dec. 31, 2011	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2011 Ross Smith Energy Group Ltd. ("RSEG")	Dec. 31, 2010 Majestic Research Corp.	Oct. 31, 2011 U.S. Operations	Jun. 30, 2011 U.S. Operations	Dec. 31, 2011 U.S. Operations	Dec. 31, 2009 U.S. Operations	Dec. 31, 2011 U.S. Operations Ross Smith Energy Group Ltd. ("RSEG")	Dec. 31, 2010 U.S. Operations Majestic Research Corp.	Oct. 31, 2011 European Operations	Dec. 31, 2011 European Operations	Dec. 31, 2010 European Operations	Dec. 31, 2010 Asia Pacific Operations	Dec. 31, 2011 Asia Pacific Operations	Jun. 30, 2010 Australia	Dec. 31, 2011 Australia	Oct. 31, 2011 Hong Kong	Dec. 31, 2011 Hong Kong
Goodwill
Balance at the beginning of the period				$ 468,479	$ 425,301					$ 439,294	$ 390,721				$ 28,484	$ 28,467	$ 6,113	$ 701
Impairment losses	(4,282)	(225,035)	(5,375)	(229,317)	(5,375)				(225,035)	(225,035)							(5,375)		(5,375)	(5,375)
Acquisition						30,715	48,573					30,715	48,573
ITG Investment Research price adjustment				144						144
Currency translation adjustment				(11)	(20)					(13)					2	17	(37)
Balance at the end of the period	$ 274,292			$ 274,292	$ 468,479				$ 470,100	$ 245,105	$ 390,721				$ 28,486	$ 28,484	$ 701	$ 701	$ 5,400
Percentage of fair value of goodwill in excess of carrying value								29.00%		20.00%				29.00%	30.00%						233.00%	227.00%