Carrying amount as of the balance sheet date, which is the cumulative amount paid and (if applicable) the fair value of any noncontrolling interest in the acquiree, adjusted for any amortization recognized prior to the adoption of any changes in generally accepted accounting principles (as applicable) and for any impairment charges, in excess of the fair value of net assets acquired in one or more business combination transactions.

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+ Details

- Definition

Loss recognized during the period that results from the write-down of goodwill after comparing the implied fair value of reporting unit goodwill with the carrying amount of that goodwill. Goodwill is assessed at least annually for impairment.

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+ Details

Goodwill and Other Intangibles (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended		3 Months Ended		9 Months Ended	3 Months Ended	9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011 U.S. Operations	Jun. 30, 2011 U.S. Operations	Sep. 30, 2011 U.S. Operations	Sep. 30, 2011 Other reporting units	Sep. 30, 2011 European Operations.	Sep. 30, 2011 Asia Pacific Operations.	Dec. 31, 2010 Asia Pacific Operations.
Changes in the carrying amount of goodwill
Balance at the beginning the period	$ 468,479		$ 245,100	$ 470,100	$ 439,294		$ 28,484	$ 701	$ 701
Impairment loss	(225,035)	(5,375)		(225,000)	(225,035)
Acquisition of Ross Smith Energy	30,715				30,715
ITG Investment Research price adjustment	144				144
Currency translation adjustment	(19)				(20)		1
Balance at the end the period	$ 274,284		$ 245,098	$ 245,100	$ 245,098		$ 28,485	$ 701	$ 701
Percentage of the excess of fair value of goodwill over carrying value, low end of range (as a percent)						29.00%
Percentage excess of fair value of goodwill over carrying value, high end of the range (as a percent)						233.00%
Percentage of the excess of fair value of goodwill over carrying value (as a percent)			29.00%