Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating activities:
Consolidated net income (loss)	$ (26,651)	$ 60,762	$ 25,598
Non-cash items included in consolidated net income:
Depreciation and amortization	3,114	3,243	3,433
Net investment (gains) losses	258	255	(234)
Restricted stock units recognized	40,597	45,880	47,071
Deferred taxes	14,594	(7,457)	(6,058)
(Gain) loss on fair value of contingent obligation	(1,332)	1,448	503
Changes in operating assets and liabilities:
Advisory fees receivable	3,896	(3,710)	17,341
Other receivables and assets	449	1,509	(1,779)
Deferred tax asset, net	0	7,668	7,882
Compensation payable	(11,505)	15,394	(4,271)
Accounts payable and accrued expenses	5,409	(706)	(5,747)
Current income taxes payable	(13,657)	(52)	9,012
Net cash provided by operating activities	15,172	124,234	92,751
Investing activities:
Distributions from investments, net	221	937	832
Purchases of property and equipment	(2,555)	(1,737)	(2,242)
Contingent obligation due selling unitholders of Cogent	0	0	13,144
Cogent acquisition	0	0	(45,265)
Net cash used in investing activities	(2,334)	(800)	(33,531)
Financing activities:
Proceeds from revolving bank loan	69,355	105,999	80,000
Repayment of revolving bank loan	(133,425)	(81,729)	(75,800)
Proceeds from bank term loans	0	0	45,000
Repayment of bank term loans	(16,875)	(16,875)	(11,250)
Proceeds from secured term loan, net	339,048	0	0
Proceeds from Issuance of Common Stock	20,000	0	0
Dividends paid	(47,552)	(61,609)	(58,940)
Purchase of treasury stock	(79,561)	(28,186)	(11,902)
Net tax benefit (cost) from the delivery of restricted stock units and payment of dividend equivalents	0	(4,883)	(5,944)
Net cash provided by (used in) financing activities	150,990	(87,283)	(38,836)
Effect of exchange rate changes on cash and cash equivalents	5,505	(7,800)	(1,362)
Net increase in cash and cash equivalents	169,333	28,351	19,022
Cash and cash equivalents, beginning of year	98,313	69,962	50,940
Cash and cash equivalents, end of year	267,646	98,313	69,962
Supplemental disclosure of cash flow information:
Cash paid for interest	6,567	2,944	2,427
Cash paid for taxes, net of refunds	$ 26,026	$ 28,979	$ 14,445