Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash flows from operating activities
Net income (loss)	$ 151,999	$ 132,174
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Bad debt expense	415	1,521
Depreciation and amortization	3,290	2,570
(Income) loss from equity method investments	(3,641)	(4,565)
Equity-based compensation	88,776	72,912
Deferred tax provision	6,333	13,746
Gain on equity method investment	0	(31,971)
Other	4,656	4,067
Changes in assets and liabilities:
Accounts receivable	1,526	(28,588)
Accrued and other receivables	(18,724)	(4,594)
Prepaid expenses and other assets	636	(7,079)
Deferred compensation	(870)	(321)
Compensation payable	(2,768)	(21,644)
Accounts payable and accrued expenses	(1,247)	(4,864)
Deferred revenue	1,640	876
Dividends received	2,737	11,672
Other liabilities	(2,168)	(628)
Net cash provided by (used in) operating activities	232,590	135,284
Cash flows from investing activities
Purchase of investments	(148,027)	(171,764)
Proceeds from sales of investments	98,860	88,750
Note payments received from employees	366	705
Notes issued to employees	0	(400)
Purchase of equipment and leasehold improvements	(4,888)	(4,553)
Net cash provided by (used in) investing activities	(53,689)	(87,262)
Cash flows from financing activities
Dividends and distributions	(286,145)	(232,284)
Payments under tax receivable agreement	0	(5,032)
Proceeds from exercise of stock options	6,781	5,571
Payments to settle employee tax obligations on share-based awards	(24,692)	(9,832)
Class A partnership units and other equity purchased	(293)	(229)
Net cash provided by (used in) financing activities	(304,349)	(241,806)
Effect of exchange rate fluctuations on cash, cash equivalents, and restricted cash	(778)	2,588
Net increase (decrease) in cash, cash equivalents, and restricted cash	(126,226)	(191,196)
Cash, cash equivalents, and restricted cash, beginning of period	213,894	319,585
Cash, cash equivalents, and restricted cash, end of period	87,668	128,389
Cash paid during the period for:
Income taxes	15,850	26,196
Dividends paid, declared in the prior year	0	68,066
Other non-cash activity:
Dividend equivalents issued	44,727	20,911
Class A Partnership Units or other equity converted into Class A Common Stock	39,987	52,240
Cumulative Effect Adjustment upon Adoption of ASU	0	658
Cumulative Effect Adjustment upon Adoption of ASU	3,155
Forfeiture of fully-vested Group LP units or other equity units	$ 677	$ 36