Consolidated Statements Of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Cash Flows From Operating Activities:
Net income	$ 99,439	$ 88,761
Adjustments to reconcile net income to net cash used in operating activities:
Depreciation and amortization	10,290	6,664
Amortization of loans and advances to financial advisors and other employees	21,596	19,141
Amortization of premium on investment portfolio	8,727	5,646
Provision for loan losses and allowance for loans and advances to financial advisors and other employees	1,611	2,658
Amortization of intangible assets	3,593	2,738
Deferred income taxes	2,102	16,487
Stock-based compensation	32,119	27,072
(Gains)/losses on sale of investments	(2,174)	2,884
Other, net	(6,429)	(3,871)
Receivables:
Brokerage clients	(182,761)	(56,146)
Brokers, dealers, and clearing organizations	(72,766)	(85,843)
Securities purchased under agreements to resell	131,866	(156,782)
Financial instruments owned, including those pledged	2,641	(37,363)
Loans originated as held for sale	(272,301)	(404,200)
Proceeds from mortgages held for sale	333,478	373,919
Loans and advances to financial advisors and other employees	(50,216)	(5,599)
Other assets	(24,357)	(69,119)
Increase/(decrease) in operating liabilities, net of liabilities assumed:
Brokerage clients	(200,229)	(29,277)
Brokers, dealers, and clearing organizations	21,639	18,703
Drafts	(4,263)	(30,872)
Financial instruments sold, but not yet purchased	31,754	180,672
Other liabilities and accrued expenses	(252,199)	(238,121)
Net cash used in operating activities	(366,840)	(371,848)
Cash Flows From Investing Activities:
Maturities and principal paydowns of available-for-sale securities	93,349	129,926
Calls and principal paydowns of held-to-maturity securities	114,535	230,172
Sale or maturity of investments		9,575
Increase in bank loans, net	(195,186)	(130,566)
Payments for:
Purchase of fixed assets	(72,868)	(4,586)
Purchase of available-for-sale securities	(250)	(92,145)
Purchase of held-to-maturity securities		(379,490)
Acquisitions, net of cash received	(28,523)	(29,209)
Net cash used in investing activities	(88,943)	(266,323)
Cash Flows From Financing Activities:
Proceeds from borrowings, net	218,315	60,000
Proceeds from Federal Home Loan Bank advances, net		82,000
Repayments of Federal Home Loan Bank advances, net	(290,000)
Payment of contingent consideration	(2,994)	(7,900)
Increase/(decrease) in securities sold under agreements to repurchase	(93,419)	112,498
Decrease in bank deposits, net	(813,736)	(82,312)
Increase in securities loaned	132,952	209,590
Tax payments related to shares withheld for stock-based compensation plans	(27,847)	(36,534)
Proceeds from preferred stock issuance, net	155,294
Proceeds from non-controlling interests	26,800
Proceeds from stock option exercises		774
Repurchase of common stock	(53,869)	(2,839)
Cash dividends on preferred stock	(2,344)	(2,344)
Cash dividends paid to common stock and equity-award holders	(12,944)	(8,629)
Other	(490)
Net cash (used in)/provided by financing activities	(764,282)	324,304
Effect of exchange rate changes on cash	2,156	3,736
Decrease in cash and cash equivalents	(1,217,909)	(310,131)
Cash and cash equivalents at beginning of period	2,069,374	787,085
Cash and cash equivalents at end of period	851,465	476,954
Supplemental disclosure of cash flow information:
Cash paid for income taxes, net of refunds/(refunds, net of taxes paid)	466	(21,076)
Cash paid for interest	49,425	25,368
Noncash financing activities:
Unit grants, net of forfeitures	$ 92,344	$ 90,678