Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 231,331	$ 152,087
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization of property	15,371	16,630
Amortization of deferred expenses and share-based incentive compensation	209,127	199,217
Amortization and other acquisition-related costs	4,831	974
Deferred tax provision	39,936	25,159
(Increase) decrease in operating assets:
Deposits with banks and short-term investments	(286,538)	(271,010)
Cash deposited with clearing organizations and other segregated cash	(4,592)	1,697
Receivables-net	2,227	120
Investments	30,454	51,342
Other assets	(88,178)	(52,586)
Increase (decrease) in operating liabilities:
Deposits and other payables	305,645	207,503
Accrued compensation and benefits and other liabilities	(181,227)	(312,862)
Net cash provided by operating activities	278,387	18,271
CASH FLOWS FROM INVESTING ACTIVITIES:
Additions to property	(9,408)	(11,118)
Disposals of property	193	159
Net cash used in investing activities	(9,215)	(10,959)
Proceeds from:
Contributions from noncontrolling interests		93
Excess tax benefits from share-based incentive compensation		2,340
Other financing activities		8,004
Payments for:
Capital lease obligations	(7,320)	(835)
Distributions to noncontrolling interests	(1,743)	(708)
Payments under tax receivable agreement	(776)	(10,086)
Purchase of Class A common stock	(184,892)	(194,729)
Class A common stock dividends	(242,427)	(242,085)
Settlement of vested share-based incentive compensation	(66,085)	(54,164)
Other financing activities	(8,970)	(2,327)
Net cash used in financing activities	(512,213)	(494,497)
EFFECT OF EXCHANGE RATE CHANGES ON CASH	39,895	1,556
NET DECREASE IN CASH AND CASH EQUIVALENTS	(203,146)	(485,629)
CASH AND CASH EQUIVALENTS—January 1	1,158,785	1,132,083
CASH AND CASH EQUIVALENTS—June 30	$ 955,639	$ 646,454