Related Party Transactions (Details) (USD $)	3 Months Ended			3 Months Ended																3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012	Mar. 31, 2013 Affiliated Entity Asset Management Income	Mar. 31, 2012 Affiliated Entity Asset Management Income	Mar. 31, 2013 Affiliated Entity Fees Receivable	Dec. 31, 2012 Affiliated Entity Fees Receivable	Mar. 31, 2013 Affiliated Entity Fees Receivable Raimus Alternative Solutions L.L.C.	Dec. 31, 2012 Affiliated Entity Fees Receivable Raimus Alternative Solutions L.L.C.	Dec. 31, 2004 Affiliated Entity Fees Receivable Raimus Alternative Solutions L.L.C.	Mar. 31, 2013 Affiliated Entity Fees Payable	Dec. 31, 2012 Affiliated Entity Fees Payable	Mar. 31, 2013 Employees	Dec. 31, 2012 Employees	Apr. 30, 2011 Equity Method Investee Starboard Value L.P.	Apr. 30, 2011 Equity Method Investee Starboard Value L.P. LIBOR	Mar. 31, 2013 Equity Method Investee Due from Related Parties Starboard Value L.P.	Mar. 31, 2013 Investor	Dec. 31, 2012 Investor	Mar. 31, 2013 Minimum	Mar. 31, 2013 Maximum
Related Party Transaction [Line Items]
Fees receivable from related parties						$ 10,900,000	$ 13,600,000
Reimbursement to affiliated funds				500,000	300,000
Fees payable to related parties											1,400,000	1,700,000
Receivables acquired in business combination								200,000	300,000	9,600,000
Due from employees													4,900,000	5,100,000
Forgivable Loan Balances													2,300,000	2,300,000
Deferred Compensation Arrangement with Individual, Award Vesting Period																				1 year	3 years
Amortization on Forgivable Loans	400,000	400,000
Credit agreement with related party, maximum loan amount															3,000,000.0
Credit agreement with related party, interest rate spread																3.75%
Credit agreement with related party, loan receivable																	1,500,000
Due to Affiliate	$ 618,000		$ 662,000															$ 400,000	$ 400,000