Goodwill and Intangible Assets (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended			6 Months Ended								6 Months Ended	12 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011	Jun. 30, 2012 Customer relationships Minimum	Jun. 30, 2012 Customer relationships Maximum	Jun. 30, 2012 Customer relationships MBS & Rates	Dec. 31, 2011 Customer relationships MBS & Rates	Jun. 30, 2012 Customer relationships Credit Products	Dec. 31, 2011 Customer relationships Credit Products	Jun. 30, 2012 Customer relationships ClearPoint	Dec. 31, 2011 Customer relationships ClearPoint	Jun. 30, 2012 Trade name	Dec. 31, 2011 Trade name Investment Banking	Jun. 30, 2012 Trade name Investment Banking
Intangible assets (amortizable):
Gross carrying amount								$ 641	$ 641	$ 795	$ 795	$ 803	$ 803		$ 7,300	$ 4,066
Accumulated amortization								(436)	(410)	(689)	(610)	(151)	(100)		(874)	(965)
Impairment of intangible asset															(3,234)
Net carrying amount	4,064		4,064		4,311			205	231	106	185	652	703		3,192	3,101
Amortization period						3 years	12 years							20 years
Remaining amortization period														16 years
Total amortization expense	$ 100	$ 700	$ 247	$ 1,528