Commitments and Contingencies (Details 2) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Future Minimum Lease Payments
2013 (Remaining)	$ 6,495,000
2014	6,922,000
2015	6,293,000
2016	5,850,000
2017	5,538,000
Thereafter	38,364,000
Total	69,462,000
Sublease Rental Income
2013 (Remaining)	896,000
2014	860,000
2015	502,000
Total	2,258,000
Net Lease Payments
2013 (Remaining)	5,599,000
2014	6,062,000
2015	5,791,000
2016	5,850,000
2017	5,538,000
Thereafter	38,364,000
Total	67,204,000
Rental expense, net of sublease rental income	1,200,000	1,000,000
Letters of Credit
Contingent liability under stand-by letter of credit agreements	4,900,000		4,900,000
Other
Deposit with FICC	$ 6,300,000		$ 8,800,000