Related Party Transactions (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Related Party Transaction [Line Items]
Fees receivable, net of allowance of $1,648 and $0, respectively	$ 110,954		$ 110,954		$ 45,883
Reimbursable to affiliated funds	100		100
Due from related parties	37,407		37,407		39,629
Redeemable non-controlling interests, Related Party	421,661		421,661		379,205
Net income (loss) attributable to redeemable non-controlling interests in consolidated subsidiaries and funds	(5,162)	$ (18,478)	(35,412)	$ 2,524
Employees
Related Party Transaction [Line Items]
Redeemable non-controlling interests, Related Party	29,000		29,000		32,900
Net income (loss) attributable to redeemable non-controlling interests in consolidated subsidiaries and funds	(1,600)	(2,900)	(7,200)	(4,200)
Employee Loans
Related Party Transaction [Line Items]
Due from employees	11,400		11,400		9,200
Forgivable Loan Balances	5,400		5,400		3,300
Amortization on Forgivable Loans	600	200	$ 1,600	$ 900
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 of $1,648 and $0, respectively	14,700		$ 14,700		12,600
Affiliated Entity | Fees Payable
Related Party Transaction [Line Items]
Fees payable to related parties					300
Investor
Related Party Transaction [Line Items]
Due to Affiliate	600		600		700
Other Funds
Related Party Transaction [Line Items]
Due from related parties	11,600		11,600		11,800
Starboard Value LP
Related Party Transaction [Line Items]
Effective interest rate				5.00%
Interest Income, Related Party	200	$ 200	600	$ 500
Due from related parties	$ 14,400		$ 14,400		$ 18,700
Finance Period			5 years