Commitments and Contingencies (Details) (USD $)	3 Months Ended		6 Months Ended													6 Months Ended			6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014 Affiliated Entity	Jun. 30, 2014 Healthcare Royalty Partners Affiliated Entity	Jun. 30, 2014 Starboard Leaders Fund LP Affiliated Entity	Jun. 30, 2014 Formation 8 Partners Fund I LP Affiliated Entity	Jun. 30, 2014 Equipment Leases		Jun. 30, 2014 Service Payments	Jun. 30, 2014 Facility Leases [Member]		Jun. 30, 2014 Clawback Obligation [Member]	Dec. 31, 2013 Clawback Obligation [Member]	Jun. 30, 2014 Commitment to Invest Healthcare Royalty Partners Affiliated Entity Minimum	Jun. 30, 2014 Commitment to Invest Healthcare Royalty Partners Affiliated Entity Maximum	Apr. 30, 2013 Commitment to Invest Starboard Leaders Fund LP Affiliated Entity	Jun. 30, 2014 Commitment to Invest Formation 8 Partners Fund I LP Affiliated Entity	Jun. 30, 2014 Unfunded Commitments cowenfund
Lease Obligations
Net rent expense	$ 4,000,000	$ 4,200,000	$ 8,200,000	$ 7,900,000
Future minimum annual lease and service payments
Contractual Obligation, Due in Remainder of Fiscal Year									1,454,000	[1]	7,090,000	9,303,000	[2]
Contractual Obligation, Due in Second Year									2,603,000	[1]	9,472,000	17,817,000	[2]
Contractual Obligation, Due in Third Year									2,284,000	[1]	4,310,000	14,711,000	[2]
Contractual Obligation, Due in Fourth Year									2,198,000	[1]	2,720,000	11,591,000	[2]
Contractual Obligation, Due in Fifth Year									2,198,000	[1]	2,609,000	11,296,000	[2]
Contractual Obligation, Due after Fifth Year									813,000	[1]	22,000	41,601,000	[2]
Future minimum annual lease and service payments									11,550,000	[1]	26,223,000	106,319,000	[2]
Sublease income related to operating leases	500,000	400,000	800,000	700,000
Contractual obligation						43,700,000								6,200,000	6,200,000			1,000,000
Number of real estate investments, in investments																				2
Expected call period																2 years	5 years
Funding toward commitments						32,900,000	700,000
Other commitments, unfunded amount					$ 11,500,000			$ 5,500,000
Term of capital commitment																			4 years

[1] Equipment Leases include the Company's commitments relating to operating and capital leases. See Note 14 for further information on the capital lease minimum payments which are included in the table.

[2] The Company has entered into various agreements to sublease certain of its premises. The Company recorded sublease income related to these leases of $0.5 million and $0.4 million for the three months ended June 30, 2014 and 2013 and $0.8 million and $0.7 million for the six months ended June 30, 2014 and 2013.