Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities
Net income	$ 92,491	$ 63,704	$ 25,826
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for deferred income taxes	(745)	4,116	11,191
Depreciation and amortization	23,873	23,277	29,910
Amortization of deferred financing fees and accretion expense	3,892	2,875	6,606
Share-based and deferred compensation	22,124	17,346	17,179
Change in fair value of contingent consideration obligations	19,886	(37)	(294)
Loss on other receivable		998	4,429
Unrealized (appreciation) depreciation on investments	(1,887)	2,872	(620)
Net (gain) loss on equity method investment	(2,683)	730	427
Loss on debt extinguishment	9,860	6,058	330
Changes in operating assets and liabilities:
Investment management fees receivable	(10,988)	4,284	1,333
Fund administration and distribution fees receivable	(11,380)	772	679
Other receivables	322	5,640	21,456
Prepaid expenses	(2,141)	(215)	(1,231)
Other assets	(836)	57	79
Accounts payable	(336)	278	(3,550)
Accrued compensation and benefits	18,700	931	(10,607)
Accrued expenses	64,597	261	(5,701)
Deferred compensation plan liability	(236)	(48)	(181)
Other liabilities	2,871	446	(1,092)
Net cash provided by operating activities	227,384	134,345	96,169
Cash flows from investing activities
Purchases of property and equipment	(5,239)	(2,546)	(5,105)
Disposal of property and equipment due to restructuring			3,006
Purchases of trading securities	(6,594)	(7,704)	(9,567)
Proceeds from sales of trading securities	2,749	2,772	5,166
Purchases of available-for-sale securities	(182)	(71)	(111)
Proceeds from sales of available-for-sale securities	158		79
Proceeds from (investments in) equity method investment	10,572	(4,000)	(2,000)
Acquisition of business	(851,276)
Net cash used in investing activities	(849,812)	(11,549)	(8,532)
Cash flows from financing activities
Issuance of common stock, net of costs			3,193
Repurchase of common stock	(15,535)	(8,178)	(4,654)
Payments of taxes related to net share settlement of equity awards	(7,659)	(510)
Issuance of Class A common stock under 2018 ESPP		26
Payment of equity awards modified to liabilities			(1,836)
Excess tax benefits on share-based compensation			261
Proceeds from long-term senior debt	1,088,503	359,100	125,000
Repayment of draw on line of credit			(3,500)
Payment of debt financing fees	(19,820)	(2,508)	(1,733)
Repayment of long-term senior debt	(428,000)	(579,750)	(63,877)
Repayment of promissory note	(96)	(575)	(575)
Payment of dividends	(7,436)	(831)	(135,171)
Payment of consideration for acquisition	(6,017)	(4,447)	(8,381)
Net cash provided by (used in) financing activities	608,016	(84,161)	(91,273)
Effect of changes of foreign exchange rate on cash and cash equivalents	42	(65)	116
Net (decrease) increase in cash and cash equivalents	(14,370)	38,570	(3,520)
Cash and cash equivalents, beginning of period	51,491	12,921	16,441
Cash and cash equivalents, end of period	37,121	51,491	12,921
Supplemental cash flow information
Cash paid for interest	23,454	17,530	41,489
Cash paid for income taxes	24,634	17,993	$ 758
Class A
Cash flows from financing activities
Issuance of common stock, net of costs	62	156,549
Payment of Class A common stock deferred offering costs		(4,287)
Class B
Cash flows from financing activities
Issuance of common stock, net of costs	$ 4,014	1,250
Payment of Class A common stock deferred offering costs		$ (4,300)