Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 110,430	$ 70,723
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization of property	7,662	8,389
Amortization of deferred expenses and share-based incentive compensation	92,766	117,140
Amortization and other acquisition-related costs	3,574	644
Deferred tax provision	17,520	11,586
(Increase) decrease in operating assets:
Deposits with banks and short-term investments	(146,251)	19,498
Cash deposited with clearing organizations and other segregated cash	(4,533)	1,474
Receivables-net	115,043	(11,757)
Investments	66,979	86,169
Other assets	(73,026)	(46,592)
Increase (decrease) in operating liabilities:
Deposits and other payables	146,271	(2,729)
Accrued compensation and benefits and other liabilities	(242,052)	(354,436)
Net cash (used in) provided by operating activities	94,383	(99,891)
CASH FLOWS FROM INVESTING ACTIVITIES:
Additions to property	(3,847)	(5,454)
Disposals of property	135	104
Net cash used in investing activities	(3,712)	(5,350)
Proceeds from:
Contributions from noncontrolling interests		93
Excess tax benefits from share-based incentive compensation		2,720
Payments for:
Capital lease obligations	(396)	(417)
Distributions to noncontrolling interests	(1,001)	(424)
Payments under tax receivable agreement	(736)	(10,086)
Purchase of Class A common stock	(106,048)	(83,140)
Class A common stock dividends	(192,264)	(194,382)
Settlement of vested share-based incentive compensation	(61,478)	(50,455)
Other financing activities	(7,947)	(1,614)
Net cash used in financing activities	(369,870)	(337,705)
EFFECT OF EXCHANGE RATE CHANGES ON CASH	11,869	12,187
NET DECREASE IN CASH AND CASH EQUIVALENTS	(267,330)	(430,759)
CASH AND CASH EQUIVALENTS—January 1	1,158,785	1,132,083
CASH AND CASH EQUIVALENTS—March 31	$ 891,455	$ 701,324