Consolidated Statements Of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Cash Flows From Operating Activities:
Net income	$ 209,196	$ 176,048
Adjustments to reconcile net income to net cash used in operating activities:
Depreciation and amortization	20,410	13,467
Amortization of loans and advances to financial advisors and other employees	45,266	40,552
Amortization of premium on investment portfolio	15,083	11,477
Provision for loan losses and allowance for loans and advances to financial advisors and other employees	4,838	6,595
Amortization of intangible assets	7,140	5,740
Deferred income taxes	511	6,563
Stock-based compensation	54,443	47,642
(Gains)/losses on sale of investments	(14,484)	7,533
Other, net	(25,671)	(3,241)
Receivables:
Brokerage clients	(145,463)	(56,656)
Brokers, dealers, and clearing organizations	(250,609)	(213,053)
Securities purchased under agreements to resell	103,328	(53,821)
Financial instruments owned, including those pledged	(52,227)	(133,739)
Loans originated as held for sale	(702,007)	(759,874)
Proceeds from mortgages held for sale	759,773	779,761
Loans and advances to financial advisors and other employees	(107,932)	(37,174)
Other assets	(48,951)	(53,251)
Increase/(decrease) in operating liabilities, net of liabilities assumed:
Brokerage clients	(49,014)	(107,705)
Brokers, dealers, and clearing organizations	94,795	82,234
Drafts	(11,503)	(40,690)
Financial instruments sold, but not yet purchased	8,982	165,818
Other liabilities and accrued expenses	(226,315)	(99,005)
Net cash used in operating activities	(310,411)	(214,779)
Cash Flows From Investing Activities:
Maturities and principal paydowns of available-for-sale securities	410,311	458,662
Calls and principal paydowns of held-to-maturity securities	256,404	338,328
Sale or maturity of investments	694	11,942
Increase in bank loans, net	(454,048)	(405,094)
Payments for:
Purchase of fixed assets	(101,683)	(12,299)
Purchase of available-for-sale securities	(500)	(204,907)
Purchase of held-to-maturity securities		(1,162,087)
Purchase of investments		(7,578)
Acquisitions, net of cash received	(28,236)	(29,209)
Net cash provided by/(used in) investing activities	82,942	(1,012,242)
Cash Flows From Financing Activities:
Repayments of borrowings, net	(62,810)	(13,000)
(Repayments of)/proceeds from Federal Home Loan Bank advances, net	(290,000)	15,000
Payment of contingent consideration	(6,925)	(11,909)
Increase in securities sold under agreements to repurchase	202,579	280,630
(Decrease)/increase in bank deposits, net	(962,552)	478,914
Increase in securities loaned	100,086	381,349
Tax payments related to shares withheld for stock-based compensation plans	(28,992)	(38,397)
Proceeds from preferred stock issuance, net	154,988
Proceeds from non-controlling interests	26,800
Proceeds from stock option exercises		2,278
Repurchase of common stock	(124,966)	(45,883)
Cash dividends on preferred stock	(7,632)	(4,688)
Cash dividends paid to common stock and equity-award holders	(21,352)	(17,223)
Other	(1,407)
Net cash (used in)/provided by financing activities	(1,022,183)	1,027,071
Effect of exchange rate changes on cash	(1,134)	(2,098)
Decrease in cash, cash equivalents, and cash segregated for regulatory purposes	(1,250,786)	(202,048)
Cash, cash equivalents, and cash segregated for regulatory purposes at beginning of period	2,069,374	787,085
Cash, cash equivalents, and cash segregated for regulatory purposes at end of period	818,588	585,037
Supplemental disclosure of cash flow information:
Cash paid for income taxes, net of refunds/(refunds, net of taxes paid)	84,806	(17,286)
Cash paid for interest	103,112	62,720
Noncash financing activities:
Unit grants, net of forfeitures	$ 102,519	$ 104,703