Condensed Consolidated Statements of Changes in Equity - USD ($) $ in Thousands	Total	Additional Paid-in-Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Non-Controlling interest AOG	Non-Controlling interest Consolidated Funds	Preferred Class A	Class A common stock	Class A common stock Common Stock	Class C common stock Common Stock
Beginning balance at Dec. 31, 2018	$ 1,394,341	$ 326,007	$ (29,336)	$ (8,524)	$ 302,780	$ 503,637	$ 298,761		$ 1,016
Increase (Decrease) in Stockholders' Equity
Relinquished with deconsolidation of funds	(55)					(55)
Changes in ownership interests and related tax benefits	(18,397)	(6,339)			(12,073)				15
Capital contributions	55,911				1,876	54,035
Dividends/Distributions	(101,640)		(35,367)		(40,112)	(20,736)	(5,425)
Net income	121,576		39,524		59,003	17,624	5,425
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	332,305	(25,179)	(7,240)	327,300	552,846	298,761		1,031
Beginning balance at Dec. 31, 2018	1,394,341	326,007	(29,336)	(8,524)	302,780	503,637	298,761		1,016
Increase (Decrease) in Stockholders' Equity
Repurchases of Class A common stock								$ (10,400)
Ending balance at Sep. 30, 2019	1,842,782	507,531	(44,308)	(11,010)	450,985	639,676	298,761		1,147
Beginning balance at Mar. 31, 2019	1,479,824	332,305	(25,179)	(7,240)	327,300	552,846	298,761		1,031
Increase (Decrease) in Stockholders' Equity
Changes in ownership interests and related tax benefits	(11,508)	(32,128)			20,615				5
Repurchases of Class A common stock	(10,449)	(10,445)							(4)
Capital contributions	61,464					61,464
Dividends/Distributions	(92,529)		(36,782)		(40,103)	(10,219)	(5,425)
Net income	74,878		26,714		34,393	8,346	5,425
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	78,751							43
Ending balance at Jun. 30, 2019	1,602,324	379,789	(35,247)	(8,879)	352,882	613,943	298,761		1,075
Increase (Decrease) in Stockholders' Equity
Changes in ownership interests and related tax benefits	1,209	(94,004)			95,212				1
Capital contributions	256,096	206,635				49,391			70
Dividends/Distributions	(125,982)		(36,967)		(48,970)	(34,620)	(5,425)
Net income	91,875		27,906		42,636	15,908	5,425
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	4,295							1
Ending balance at Sep. 30, 2019	1,842,782	507,531	(44,308)	(11,010)	450,985	639,676	298,761		1,147
Increase (Decrease) in Stockholders' Equity
Changes in ownership interests and related tax benefits	83	(1,505)			1,587				1
Capital contributions	7,961					7,961
Dividends/Distributions	(121,498)		(39,552)		(45,814)	(30,707)	(5,425)
Net income	84,475		33,040		48,184	(2,174)	5,425
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	7,417							4
Ending balance at Dec. 31, 2019	1,858,598	525,244	(50,820)	(6,047)	472,288	618,020	298,761		1,152	$ 0
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)	(196,670)			122,551				40
Issuances of common stock	383,334	382,061							121	1,152
Capital contributions	175,277				42,012	133,265
Dividends/Distributions	(125,755)		(51,090)		(55,748)	(13,492)	(5,425)
Net income	(275,797)		(36,461)		(78,355)	(166,406)	5,425
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	19,540							11
Ending balance at Mar. 31, 2020	1,975,596	746,595	(138,371)	(10,849)	514,166	562,818	298,761		1,324	1,152
Increase (Decrease) in Stockholders' Equity
Consolidation and deconsolidation of funds, net	1,475					1,475
Changes in ownership interests and related tax benefits	94	(9,702)			9,796				4	(4)
Expenses incurred upon issuance of common stock	(181)	(181)
Capital contributions	(9,341)				229	(9,570)
Dividends/Distributions	(259,831)		(57,620)		(59,949)	(136,837)	(5,425)
Net income	216,676		50,946		75,119	85,186	5,425
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	47,865							25
Ending balance at Jun. 30, 2020	2,003,748	800,077	(145,045)	(11,237)	552,490	506,201	298,761		1,353	1,148
Increase (Decrease) in Stockholders' Equity
Changes in ownership interests and related tax benefits	(3,751)	(122,555)			118,804				2	(2)
Issuances of common stock	305,338	305,261							77	0
Capital contributions	499	481			0	18
Dividends/Distributions	(135,393)		(61,159)		(49,391)	(19,418)	(5,425)
Net income	142,334		42,120		52,162	42,627	5,425
Currency translation adjustment, net of tax	16,251			4,450	4,128	7,673
Equity compensation	30,337	16,921			13,416
Stock option exercises	11,518	11,512							6
Ending balance at Sep. 30, 2020	$ 2,370,881	$ 1,011,697	$ (164,084)	$ (6,787)	$ 691,609	$ 537,101	$ 298,761		$ 1,438	$ 1,146