Commitments and Contingencies (Details) (USD $)	12 Months Ended												12 Months Ended			1 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 Equipment Leases [Member]		Dec. 31, 2012 Service Payments [Member]	Dec. 31, 2012 Facility Leases [Member]		Dec. 31, 2012 Buildings, Avenue of Americas [Member]	Dec. 31, 2011 Buildings, Avenue of Americas [Member]	Dec. 31, 2012 Clawback Obligation [Member]	Dec. 31, 2012 Unfunded Commitments [Member] investments	Dec. 31, 2012 Commitment to Invest [Member] Healthcare Royalty Partners [Member] Affiliated Entity [Member]	Dec. 31, 2011 Commitment to Invest [Member] Healthcare Royalty Partners [Member] Affiliated Entity [Member] Minimum	Dec. 31, 2011 Commitment to Invest [Member] Healthcare Royalty Partners [Member] Affiliated Entity [Member] Maximum	Apr. 30, 2011 Commitment to Invest [Member] Starboard Value L.P. [Member] Affiliated Entity [Member]	Apr. 30, 2011 Commitment to Invest [Member] Formation 8 Partners Fund I [Member] Affiliated Entity [Member]
Lease Obligations
Net rent expense	$ 14,300,000	$ 16,700,000	$ 10,500,000
Future Rent Payments Liability		5,700,000
Off-market Lease, Unfavorable		2,100,000
Rent expense related to abandonment		3,600,000
Liability relating to vacating premises									2,800,000	5,700,000
Future minimum annual lease and service payments
2013				3,301,000	[1]	11,536,000	17,510,000	[2]
2014				1,548,000	[1]	8,410,000	15,433,000	[2]
2015				1,051,000	[1]	2,102,000	12,368,000	[2]
2016				194,000	[1]	196,000	11,481,000	[2]
2017				0	[1]	0	9,947,000	[2]
Thereafter				0	[1]	0	43,728,000	[2]
Future minimum annual lease and service payments				6,094,000	[1]	22,244,000	110,467,000	[2]
Sublease income related to operating leases	1,200,000	300,000	800,000
Contractual obligation											6,200,000	6,300,000	42,200,000
Number of real estate investments, in investments												2
Funding toward commitments													31,300,000				1,500,000
Commitments made																$ 15,000,000	$ 10,000,000
Expected call period														2 years	5 years

[1] Equipment Leases include the Company's commitments relating to operating and capital leases. See Note 20 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 $1.2 million, $0.3 million and $0.8 million for the years ended December 31, 2012, 2011 and 2010, respectively.