Related Party Transactions (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended		12 Months Ended
	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Related Party Transaction [Line Items]
Due from related parties	$ 32,539	$ 39,659		$ 32,539		$ 39,659
Fees receivable, net of allowance	45,787	34,413		45,787		34,413
Reimbursable to affiliated funds	100			100
Redeemable non-controlling interests, Related Party	331,883	186,911		331,883		186,911
Net income (loss) attributable to redeemable non-controlling interests in consolidated subsidiaries and funds	(18,478)		$ (4,344)	2,524	$ (10,980)
Employees
Related Party Transaction [Line Items]
Redeemable non-controlling interests, Related Party	27,700	21,300		27,700		21,300
Net income (loss) attributable to redeemable non-controlling interests in consolidated subsidiaries and funds	(2,900)		(5,500)	$ (4,200)	(10,300)
Employee Loans | Minimum
Related Party Transaction [Line Items]
Forgivable Loans, Vesting Period				1 year
Employee Loans | Maximum
Related Party Transaction [Line Items]
Forgivable Loans, Vesting Period				3 years
Affiliated Entity
Related Party Transaction [Line Items]
Fees receivable, net of allowance	5,900	6,300		$ 5,900		6,300
Affiliated Entity | Fees Payable
Related Party Transaction [Line Items]
Fees payable to related parties	100	100		100		100
Employees
Related Party Transaction [Line Items]
Due from employees	7,900	5,500		7,900		5,500
Forgivable Loan Balances	2,100	1,200		2,100		1,200
Amortization on Forgivable Loans	200		$ 600	900	$ 2,600
Investor
Related Party Transaction [Line Items]
Due to Affiliate	300	300		300		300
Other Funds
Related Party Transaction [Line Items]
Due from related parties	11,700	19,700		11,700		$ 19,700
Starboard Value LP | Equity Method Investments
Related Party Transaction [Line Items]
Interest Income, Related Party	$ 200			$ 500
Equity Method Investment, Realized Gain (Loss) on Disposal		$ 12,900
Effective interest rate						5.00%