Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash Flows From Operating Activities:
Net income	$ 522,536	$ 662,155	$ 824,858
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	60,533	50,615	45,574
Amortization of loans and advances to financial advisors and other employees	145,227	132,012	114,690
Amortization of premium on investment portfolio	9,871	12,156	17,042
Provision for credit losses and allowance for loans and advances to financial advisors and other employees	24,999	33,506	(11,502)
Amortization of intangible assets	20,929	19,595	18,188
Deferred income taxes	15,968	12,693	32,104
Stock-based compensation	140,263	135,505	119,384
Unrealized (gains)/losses on investments	(460)	11,892	2,999
Other, net	2,572	8,852	26,222
Receivables:
Brokerage clients, net	82,878	228,492	(214,033)
Brokers, dealers, and clearing organizations	5,341	156,165	(8,496)
Securities purchased under agreements to resell	(1,687)	231,704	(266,801)
Financial instruments owned, including those pledged	(131,576)	425,252	(271,475)
Loans originated as held for sale	(995,084)	(576,153)	(1,997,561)
Proceeds from loans held for sale	864,996	593,086	2,313,934
Loans and advances to financial advisors and other employees	(181,583)	(132,384)	(172,553)
Other assets	(107,859)	(66,020)	(96,700)
Increase/(decrease) in operating liabilities, net of liabilities assumed:
Brokerage clients	(35,515)	(201,588)	(92,015)
Brokers, dealers, and clearing organizations	43,060	(81,661)	6,535
Drafts	15,476	(20,405)	4,880
Financial instruments sold, but not yet purchased	12,582	(301,333)	229,708
Other liabilities and accrued expenses	(14,139)	(176,721)	247,112
Net cash provided by operating activities	499,328	1,157,415	872,094
Cash Flows From Investing Activities:
Principal paydowns, calls, maturities, and sales of available-for-sale securities	138,216	330,049	562,352
Calls and principal paydowns of held-to-maturity securities	101,240	114,741	1,751,313
Sale of fixed assets	0	0	148,375
Sale or maturity of investments	15,694	20,753	19,606
Decrease/(increase) in loans held for investment, net	1,002,320	(3,822,654)	(5,609,314)
Payments for:
Purchase of available-for-sale securities	(19,635)	(103,339)	(813,657)
Purchase of held-to-maturity securities	0	(754,306)	(2,668,221)
Purchase of investments	(29,257)	(15,551)	(23,309)
Purchase of fixed assets	(51,976)	(82,327)	(188,176)
Acquisitions, net of cash received	(111,958)	(11,903)	(144,471)
Net cash provided by/(used in) investing activities	1,044,644	(4,324,537)	(6,965,502)
Cash Flows from Financing Activities:
Increase/(decrease) in securities sold under agreements to repurchase	205,633	(173,517)	135,588
Increase in bank deposits, net	217,468	3,836,763	5,883,851
Increase/(decrease) in securities loaned	67,588	(81,114)	4,095
Tax payments related to shares withheld for stock-based compensation plans	(94,387)	(102,546)	(78,565)
Repurchase of common stock	(443,876)	(105,831)	(172,741)
Cash dividends on preferred stock	(37,281)	(37,281)	(35,587)
Cash dividends paid to common stock and equity-award holders	(162,984)	(133,747)	(66,336)
Payment of contingent consideration	(6,740)	(11,313)	(16,798)
Other financing, net	0	0	140,888
Net cash (used in)/provided by financing activities	(254,579)	3,191,414	5,794,395
Effect of exchange rate changes on cash	5,454	55,053	(3,536)
Increase/(decrease) in cash, cash equivalents, and cash segregated for regulatory purposes	1,294,847	79,345	(302,549)
Cash, cash equivalents, and cash segregated for regulatory purposes at beginning of year	2,229,002	2,149,657	2,452,206
Cash, cash equivalents, and cash segregated for regulatory purposes at end of year	3,523,849	2,229,002	2,149,657
Supplemental disclosure of cash flow information:
Cash paid for income taxes, net of refunds	183,815	217,133	288,950
Cash paid for interest	821,741	220,851	62,510
Noncash investing and financing activities:
Unit grants, net of forfeitures	188,641	194,741	156,535
Issuance of common stock for acquisitions	$ 0	$ 0	$ 90,000