Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash Flows From Operating Activities
Net Income	$ 868,573	$ 412,680	$ 353,661
Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities:
Net (Gains) Losses on Investments and Investment Securities	(24,227)	(8,681)	(13,750)
Equity Method Investments	1,105	(1,636)	403
Equity-Based and Other Deferred Compensation	422,210	367,438	360,341
Net Loss on Sale and Wind-down of Operations in Mexico in 2020 and Release of Cumulative Foreign Exchange Losses	1,250	35,247	0
Impairment of Goodwill	0	0	2,921
Noncash Lease Expense	40,761	38,626	29,259
Depreciation, Amortization and Accretion	28,655	30,002	35,730
Bad Debt Expense	(60)	6,878	10,451
Deferred Taxes	29,078	13,824	(10,503)
Decrease (Increase) in Operating Assets:
Investment Securities	(1,960)	3,559	(491)
Financial Instruments Owned and Pledged as Collateral at Fair Value	0	(1,516)	10,629
Securities Purchased Under Agreements to Resell	0	(399)	(10,541)
Accounts Receivable	16,028	(78,573)	5,241
Receivable from Employees and Related Parties	(1,622)	(1,170)	1,450
Other Assets	(4,649)	(19,043)	(58,962)
(Decrease) Increase in Operating Liabilities:
Accrued Compensation and Benefits	191,223	82,364	(180,767)
Accounts Payable and Accrued Expenses	(5,497)	(796)	(745)
Securities Sold Under Agreements to Repurchase	0	1,935	(115)
Payables to Employees and Related Parties	6,065	(7,980)	(599)
Taxes Payable	5,634	11,946	(30,221)
Other Liabilities	(187,669)	93,666	1,305
Net Cash Provided by Operating Activities	1,384,898	978,371	504,697
Cash Flows From Investing Activities
Investments Purchased	(6,660)	(143)	(3,843)
Proceeds from Redemption and Sale of Investments	20,967	0	0
Distributions of Private Equity Investments	827	650	1,893
Investment Securities:
Proceeds from Sales and Maturities of Investment Securities and Futures Contracts Activity	2,669,500	555,624	510,151
Purchases of Investment Securities and Futures Contracts Activity	(3,219,975)	(1,201,617)	(698,995)
Maturity of Certificates of Deposit	121,912	214,266	100,000
Purchase of Certificates of Deposit	(264,492)	0	(211,861)
Purchase of Furniture, Equipment and Leasehold Improvements	(27,971)	(53,330)	(70,816)
Proceeds from Sale of Business, Net of Cash Sold	0	679	0
Net Cash Provided by (Used in) Investing Activities	(705,892)	(483,871)	(373,471)
Cash Flows From Financing Activities
Issuance of Noncontrolling Interests	2,179	540	600
Distributions to Noncontrolling Interests	(67,865)	(44,915)	(54,706)
Payments Under Tax Receivable Agreement	(10,825)	(9,425)	(9,490)
Short-Term Borrowings	0	0	30,000
Repayment of Short-Term Borrowings	0	0	(30,000)
Payment of Notes Payable	(38,000)	0	0
Issuance of Notes Payable	38,000	0	205,718
Debt Issuance Costs	(355)	0	(2,032)
Purchase of Treasury Stock and Noncontrolling Interests	(729,693)	(147,411)	(333,296)
Dividends	(118,762)	(106,582)	(96,803)
Net Cash Provided by (Used in) Financing Activities	(925,321)	(307,793)	(290,009)
Effect of Exchange Rate Changes on Cash	(4,616)	7,631	2,573
Net Increase (Decrease) in Cash, Cash Equivalents and Restricted Cash	(250,931)	194,338	(156,210)
Cash, Cash Equivalents and Restricted Cash – Beginning of Period	838,224	643,886	800,096
Cash, Cash Equivalents and Restricted Cash – End of Period	587,293	838,224	643,886
SUPPLEMENTAL CASH FLOW DISCLOSURE
Payments for Interest	17,332	23,748	16,405
Payments for Income Taxes	191,970	111,319	155,478
Accrued Dividends	14,332	13,734	14,642
Amounts Due for Purchase of Noncontrolling Interest	48,297	851	0
Noncash Purchase of Noncontrolling Interest	0	0	2,701
Receipt of Equity Securities in Settlement of Accounts Receivable	$ 1,955	$ 0	$ 0