Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
CASH FLOWS FROM OPERATING ACTIVITIES:
NET INCOME	$ 161,661	$ 110,430
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization of property	8,234	7,662
Amortization of deferred expenses and share-based incentive compensation	100,892	92,766
Amortization and other acquisition-related costs	866	3,574
Deferred tax provision	6,398	17,520
(Increase) decrease in operating assets:
Receivables-net	(95,308)	115,043
Investments	74,124	66,979
Other assets	(137,635)	(73,026)
Increase (decrease) in operating liabilities:
Accrued compensation and benefits and other liabilities	(157,941)	(241,624)
Net cash (used in) provided by operating activities	(38,709)	99,324
CASH FLOWS FROM INVESTING ACTIVITIES:
Additions to property	(16,158)	(3,847)
Disposals of property	1,231	135
Net cash used in investing activities	(14,927)	(3,712)
Proceeds from:
Customer deposits		145,843
Payments for:
Capital lease obligations	(8)	(396)
Customer deposits	(100,341)
Distributions to noncontrolling interests	(1,451)	(1,001)
Payments under tax receivable agreement	(31,845)	(736)
Purchase of Class A common stock	(145,949)	(106,048)
Class A common stock dividends	(202,384)	(192,264)
Settlement of vested share-based incentive compensation	(101,043)	(61,478)
Other financing activities	(3,767)	(7,947)
Net cash used in financing activities	(586,788)	(224,027)
EFFECT OF EXCHANGE RATE CHANGES ON CASH AND CASH EQUIVALENTS AND RESTRICTED CASH	49,406	18,570
NET DECREASE IN CASH AND CASH EQUIVALENTS AND RESTRICTED CASH	(591,018)	(109,845)
CASH AND CASH EQUIVALENTS AND RESTRICTED CASH	2,454,806	1,607,483
CASH AND CASH EQUIVALENTS AND RESTRICTED CASH	$ 1,863,788	$ 1,497,638