Related Party Transactions (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 Affiliated Entity [Member] Asset Management Income [Member]	Dec. 31, 2011 Affiliated Entity [Member] Asset Management Income [Member]	Dec. 31, 2010 Affiliated Entity [Member] Asset Management Income [Member]	Dec. 31, 2012 Affiliated Entity [Member] Fees Receivable [Member]	Dec. 31, 2011 Affiliated Entity [Member] Fees Receivable [Member]	Dec. 31, 2012 Affiliated Entity [Member] Fees Receivable [Member] Raimus Alternative Solutions L.L.C. [Member]	Dec. 31, 2011 Affiliated Entity [Member] Fees Receivable [Member] Raimus Alternative Solutions L.L.C. [Member]	Dec. 31, 2004 Affiliated Entity [Member] Fees Receivable [Member] Raimus Alternative Solutions L.L.C. [Member]	Dec. 31, 2012 Affiliated Entity [Member] Fees Payable [Member]	Dec. 31, 2011 Affiliated Entity [Member] Fees Payable [Member]	Dec. 31, 2012 Employees [Member]	Dec. 31, 2011 Employees [Member]	Apr. 30, 2011 Equity Method Investee [Member] Starboard Value L.P. [Member]	Apr. 30, 2011 Equity Method Investee [Member] Starboard Value L.P. [Member] LIBOR [Member]	Dec. 31, 2012 Equity Method Investee [Member] Due from Related Parties [Member] Starboard Value L.P. [Member]	Dec. 31, 2012 Investor [Member]	Dec. 31, 2011 Investor [Member]
Related Party Transaction [Line Items]
Fees receivable from related parties							$ 13,600,000	$ 14,900,000
Reimbursement to affiliated funds				(1,500,000)	(1,600,000)	(2,400,000)
Fees payable to related parties												1,700,000	3,400,000
Receivables acquired in business combination									300,000	1,000,000	9,600,000
Due from employees														5,100,000	5,300,000
Forgivable Loan Balances														2,300,000	3,200,000
Amortization on Forgivable Loans	1,900,000	1,800,000	500,000
Credit agreement with related party, maximum loan amount																3,000,000
Credit agreement with related party, interest rate spread																	3.75%
Credit agreement with related party, loan receivable																		1,500,000
Interest Expense, Related Party	100,000
Due to Affiliate	$ 662,000	$ 1,914,000																	$ 400,000	$ 300,000