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	$ 824,858	$ 503,472	$ 449,986
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	45,574	40,863	38,369
Amortization of loans and advances to financial advisors and other employees	114,690	103,983	95,053
Amortization of premium on investment portfolio	17,042	20,739	34,229
Provision for credit losses and allowance for loans and advances to financial advisors and other employees	(11,502)	33,925	11,007
Amortization of intangible assets	18,188	19,620	16,015
Deferred income taxes	32,104	(39,071)	(6,863)
Stock-based compensation	119,384	108,217	102,190
Unrealized losses/(gains) on investments	2,999	18,908	(7,922)
Other, net	26,222	(10,326)	(38,554)
Receivables:
Brokerage clients, net	(214,033)	415,286	(17,487)
Brokers, dealers, and clearing organizations	(8,496)	78,298	(8,655)
Securities purchased under agreements to resell	(266,801)	167,078	314,892
Financial instruments owned, including those pledged	(271,475)	278,904	335,548
Loans originated as held for sale	(1,997,561)	(3,019,290)	(1,848,568)
Proceeds from mortgages held for sale	2,313,934	2,894,742	1,782,455
Loans and advances to financial advisors and other employees	(172,553)	(179,995)	(210,646)
Other assets	(96,700)	(117,471)	(36,290)
Increase/(decrease) in operating liabilities, net of liabilities assumed:
Brokerage clients	(92,015)	323,493	(210,712)
Brokers, dealers, and clearing organizations	6,535	(71,144)	63,822
Drafts	4,880	(2,021)	14,871
Financial instruments sold, but not yet purchased	229,708	(224,874)	(284,510)
Other liabilities and accrued expenses	247,112	318,480	38,631
Net cash provided by operating activities	872,094	1,661,816	626,861
Cash Flows From Investing Activities:
Principal paydowns, calls, maturities, and sales of available-for-sale securities	562,352	896,746	1,224,619
Calls and principal paydowns of held-to-maturity securities	1,751,313	159,964	482,079
Sale of fixed assets	148,375
Sale or maturity of investments	19,606	2,139	14,699
Sale of other real estate owned			8,950
Disposition of business		37,000
Increase in loans held for investment, net	(5,609,314)	(1,441,303)	(1,208,817)
Payments for:
Purchase of available-for-sale securities	(813,657)	(864,200)	(239,965)
Purchase of held-to-maturity securities	(2,668,221)	(384,700)	(243,335)
Purchase of investments	(23,309)	(21,317)	(37,563)
Purchase of fixed assets	(188,176)	(73,364)	(157,897)
Acquisitions, net of cash acquired	(144,471)	(280)	(193,097)
Net cash used in investing activities	(6,965,502)	(1,689,315)	(350,327)
Cash Flows from Financing Activities:
Proceeds from preferred stock issuance, net	290,888	217,995	154,988
Increase/(decrease) in securities sold under agreements to repurchase	135,588	(200,679)	(168,069)
Increase/(decrease) in bank deposits, net	5,883,851	2,063,916	(531,032)
Increase/(decrease) in securities loaned	4,095	(463,210)	114,135
Repayments of borrowings, net			(62,810)
Repayments of Federal Home Loan Bank advances, net		(250,000)	(290,000)
Proceeds from issuance of senior notes, net		394,030
Repayments of senior notes		(300,000)
Tax payments related to shares withheld for stock-based compensation plans	(78,565)	(75,838)	(33,268)
Redemption of preferred stock	(150,000)
Repurchase of common stock	(172,741)	(58,261)	(215,430)
Cash dividends on preferred stock	(35,587)	(27,261)	(17,319)
Cash dividends paid to common stock and equity-award holders	(66,336)	(46,497)	(41,948)
Cash paid to employees upon settlement of equity awards		(27,101)
Payment of contingent consideration	(16,798)	(28,221)	(9,526)
Proceeds from non-controlling interests			26,800
Other			(3,391)
Net cash provided by/(used in) financing activities	5,794,395	1,198,873	(1,076,870)
Effect of exchange rate changes on cash	(3,536)	6,862	4,932
(Decrease)/increase in cash, cash equivalents, and cash segregated for regulatory purposes	(302,549)	1,178,236	(795,404)
Cash, cash equivalents, and cash segregated for regulatory purposes at beginning of year	2,452,206	1,273,970	2,069,374
Cash, cash equivalents, and cash segregated for regulatory purposes at end of year	2,149,657	2,452,206	1,273,970
Supplemental disclosure of cash flow information:
Cash paid for income taxes, net of refunds	288,950	160,007	161,926
Cash paid for interest	62,510	84,821	183,012
Noncash investing and financing activities:
Unit grants, net of forfeitures	156,535	$ 125,033	$ 139,408
Issuance of common stock for acquisitions	$ 90,000