Restructuring (Details) (Equities division, USD $) In Thousands, unless otherwise specified	0 Months Ended	12 Months Ended
	Aug. 22, 2011 item	Dec. 31, 2012	Dec. 31, 2011
Restructuring
Number of employees impacted	62
Restructuring charges
Non-cash charges		$ (92)	$ 1,711
Total Restructuring expense		(447)	7,094
Changes in the company's liability related to restructuring
Balance at the beginning of the period		1,427
Restructuring expense		447	(7,094)
Less: Non-cash charges		92	(1,711)
Balance at the end of the period		108	1,427
Severance and other compensation
Restructuring charges
Cash charges			2,578
Changes in the company's liability related to restructuring
Payments for restructuring			(2,578)
Third party vendor contracts
Restructuring charges
Cash charges			1,613
Changes in the company's liability related to restructuring
Payments for restructuring		(747)	(541)
Real estate exit costs
Restructuring charges
Cash charges			597
Changes in the company's liability related to restructuring
Payments for restructuring		(217)	(247)
Legal and other related costs
Restructuring charges
Cash charges			595
Changes in the company's liability related to restructuring
Payments for restructuring			(590)
Stock-based compensation
Restructuring charges
Non-cash charges			1,395
Changes in the company's liability related to restructuring
Less: Non-cash charges			(1,395)
Asset impairments
Restructuring charges
Non-cash charges			316
Changes in the company's liability related to restructuring
Less: Non-cash charges			$ (316)