Condensed Consolidated Statements of Changes in Unitholders' Capital (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2015
Increase (decrease) in Stockholders' Equity:
Unitholders' capital, value			$ 1,885,171	$ 1,808,094
Cumulative-effect adjustment from adoption of accounting guidance					$ (122,621)
Repurchase and cancellation of units			(11,470)	(11,504)
Equity reallocation between controlling and non-controlling interests	$ (5,082)	$ (3,766)	(14,581)	(11,892)
Capital increase related to equity-based compensation			44,681	48,247
Distributions declared			(471,682)	(289,914)
Net income			569,856	378,575
Foreign currency translation adjustment, net of tax	(1,693)	(272)	(7,347)	3,309
Unrealized gain on interest-rate swap designated as cash-flow hedge, net of tax		374	60	569
Unitholders' capital, value	2,009,269	1,814,755	2,009,269	1,814,755
Paid-in Capital
Increase (decrease) in Stockholders' Equity:
Unitholders' capital, value			749,618	735,166
Cumulative-effect adjustment from adoption of accounting guidance					(12,912)
Repurchase and cancellation of units			(8,454)	(11,191)
Equity reallocation between controlling and non-controlling interests			14,581	11,892
Capital increase related to equity-based compensation			18,343	19,488
Distributions declared				(1,350)
Unitholders' capital, value	773,736	741,093	773,736	741,093
Retained Earnings
Increase (decrease) in Stockholders' Equity:
Unitholders' capital, value			54,494	0
Distributions declared			(170,034)	(99,045)
Net income			218,080	135,422
Unitholders' capital, value	102,892	36,377	102,892	36,377
Accumulated Other Comprehensive Income (Loss)
Increase (decrease) in Stockholders' Equity:
Unitholders' capital, value			1,793	(1,216)
Foreign currency translation adjustment, net of tax			(3,001)	1,337
Unrealized gain on interest-rate swap designated as cash-flow hedge, net of tax			24	230
Unitholders' capital, value	(1,184)	351	(1,184)	351
Non-controlling Interests in Consolidated Subsidiaries
Increase (decrease) in Stockholders' Equity:
Unitholders' capital, value			1,050,319	1,043,930
Cumulative-effect adjustment from adoption of accounting guidance					$ (109,709)
Repurchase and cancellation of units			(3,016)	(313)
Equity reallocation between controlling and non-controlling interests			(14,581)	(11,892)
Capital increase related to equity-based compensation			26,338	28,759
Distributions declared			(299,857)	(186,935)
Net income			350,028	241,785
Foreign currency translation adjustment, net of tax	(985)	(163)	(4,346)	1,972
Unrealized gain on interest-rate swap designated as cash-flow hedge, net of tax		223	36	339
Unitholders' capital, value	1,104,921	1,007,936	1,104,921	1,007,936
Non-controlling Interests in Consolidated Funds
Increase (decrease) in Stockholders' Equity:
Unitholders' capital, value			28,947	30,214
Distributions declared			(1,791)	(2,584)
Net income			1,748	1,368
Foreign currency translation adjustment, net of tax	0	0	0	0
Unrealized gain on interest-rate swap designated as cash-flow hedge, net of tax		0	0	0
Unitholders' capital, value	$ 28,904	$ 28,998	$ 28,904	$ 28,998
Class A Units | Common Units
Increase (decrease) in Stockholders' Equity:
Unitholders' capital (in shares)			63,032	61,970
Issuance of units (in shares)			1,800	1,240
Cancellation of units associated with forfeitures (in shares)			(21)	(51)
Repurchase and cancellation of units (in shares)			(206)	(245)
Unitholders' capital (in shares)	64,605	62,914	64,605	62,914
Class B Units | Common Units
Increase (decrease) in Stockholders' Equity:
Unitholders' capital (in shares)			91,758	91,938
Issuance of units (in shares)			524	630
Cancellation of units associated with forfeitures (in shares)				(111)
Cancellation of units (in shares)			(515)	(110)
Repurchase and cancellation of units (in shares)			(85)	(308)
Unitholders' capital (in shares)	91,682	92,039	91,682	92,039