Condensed Consolidated Statements of Changes in Equity - USD ($) $ in Thousands	Total	Preferred Class A	Class A common stock	Common Stock Class A common stock	Common Stock Class C common stock	Additional Paid-in-Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Non-Controlling interest AOG	Non-Controlling interest Consolidated Funds
Beginning balance at Dec. 31, 2018	$ 1,394,341	$ 298,761		$ 1,016		$ 326,007	$ (29,336)	$ (8,524)	$ 302,780	$ 503,637
Increase (Decrease) in Stockholders' Equity
Relinquished with deconsolidation of funds	(55)									(55)
Changes in ownership interests and related tax benefits	(18,397)			15		(6,339)			(12,073)
Capital contributions	55,911								1,876	54,035
Dividends/Distributions	(101,640)	(5,425)					(35,367)		(40,112)	(20,736)
Net income (loss)	121,576	5,425					39,524		59,003	17,624
Currency translation adjustment, net of tax	1,084							1,284	1,459	(1,659)
Equity compensation	27,004					12,637			14,367
Ending balance at Mar. 31, 2019	1,479,824	298,761		1,031		332,305	(25,179)	(7,240)	327,300	552,846
Beginning balance at Dec. 31, 2018	1,394,341	298,761		1,016		326,007	(29,336)	(8,524)	302,780	503,637
Increase (Decrease) in Stockholders' Equity
Repurchases of Class A common stock			$ (10,400)
Net income (loss)	196,454
Ending balance at Jun. 30, 2019	1,602,324	298,761		1,075		379,789	(35,247)	(8,879)	352,882	613,943
Beginning balance at Mar. 31, 2019	1,479,824	298,761		1,031		332,305	(25,179)	(7,240)	327,300	552,846
Increase (Decrease) in Stockholders' Equity
Changes in ownership interests and related tax benefits	(11,508)			5		(32,128)			20,615
Repurchases of Class A common stock	(10,449)			(4)		(10,445)
Capital contributions	61,464									61,464
Dividends/Distributions	(92,529)	(5,425)					(36,782)		(40,103)	(10,219)
Net income (loss)	74,878	5,425					26,714		34,393	8,346
Currency translation adjustment, net of tax	(1,991)							(1,639)	(1,858)	1,506
Equity compensation	23,841					11,306			12,535
Stock option exercises	78,794			43		78,751
Ending balance at Jun. 30, 2019	1,602,324	298,761		1,075		379,789	(35,247)	(8,879)	352,882	613,943
Increase (Decrease) in Stockholders' Equity
Changes in ownership interests and related tax benefits	1,209			1		(94,004)			95,212
Capital contributions	256,096			70		206,635				49,391
Dividends/Distributions	(125,982)	(5,425)					(36,967)		(48,970)	(34,620)
Net income (loss)	91,875	5,425					27,906		42,636	15,908
Currency translation adjustment, net of tax	(9,429)							(2,131)	(2,352)	(4,946)
Equity compensation	22,393					10,816			11,577
Stock option exercises	4,296			1		4,295
Ending balance at Sep. 30, 2019	1,842,782	298,761		1,147		507,531	(44,308)	(11,010)	450,985	639,676
Increase (Decrease) in Stockholders' Equity
Changes in ownership interests and related tax benefits	83			1		(1,505)			1,587
Capital contributions	7,961									7,961
Dividends/Distributions	(121,498)	(5,425)					(39,552)		(45,814)	(30,707)
Net income (loss)	84,475	5,425					33,040		48,184	(2,174)
Currency translation adjustment, net of tax	13,658							4,963	5,431	3,264
Equity compensation	23,716					11,801			11,915
Stock option exercises	7,421			4		7,417
Ending balance at Dec. 31, 2019	1,858,598	298,761		1,152	$ 0	525,244	(50,820)	(6,047)	472,288	618,020
Increase (Decrease) in Stockholders' Equity
Consolidation and deconsolidation of funds, net	(3,882)									(3,882)
Changes in ownership interests and related tax benefits	(74,079)			40		(196,670)			122,551
Issuances of common stock	383,334			121	1,152	382,061
Capital contributions	175,277								42,012	133,265
Dividends/Distributions	(125,755)	(5,425)					(51,090)		(55,748)	(13,492)
Net income (loss)	(275,797)	5,425					(36,461)		(78,355)	(166,406)
Currency translation adjustment, net of tax	(14,208)							(4,802)	(4,719)	(4,687)
Equity compensation	32,557					16,420			16,137
Stock option exercises	19,551			11		19,540
Ending balance at Mar. 31, 2020	1,975,596	298,761		1,324	1,152	746,595	(138,371)	(10,849)	514,166	562,818
Beginning balance at Dec. 31, 2019	1,858,598	298,761		1,152	0	525,244	(50,820)	(6,047)	472,288	618,020
Increase (Decrease) in Stockholders' Equity
Net income (loss)	(59,121)
Ending balance at Jun. 30, 2020	2,003,748	298,761		1,353	1,148	800,077	(145,045)	(11,237)	552,490	506,201
Beginning balance at Mar. 31, 2020	1,975,596	298,761		1,324	1,152	746,595	(138,371)	(10,849)	514,166	562,818
Increase (Decrease) in Stockholders' Equity
Consolidation and deconsolidation of funds, net	1,475									1,475
Changes in ownership interests and related tax benefits	94			4	(4)	(9,702)			9,796
Expenses incurred upon issuance of common stock	(181)					(181)
Capital contributions	(9,341)								229	(9,570)
Dividends/Distributions	(259,831)	(5,425)					(57,620)		(59,949)	(136,837)
Net income (loss)	216,676	5,425					50,946		75,119	85,186
Currency translation adjustment, net of tax	2,687							(388)	(54)	3,129
Equity compensation	28,683					15,500			13,183
Stock option exercises	47,890			25		47,865
Ending balance at Jun. 30, 2020	$ 2,003,748	$ 298,761		$ 1,353	$ 1,148	$ 800,077	$ (145,045)	$ (11,237)	$ 552,490	$ 506,201