Consolidated Statements Of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Cash Flows From Operating Activities:
Net income	$ 65,512	$ 27,055
Adjustments to reconcile net income to net cash provided by/(used in) operating activities:
Depreciation and amortization	9,022	10,629
Amortization of loans and advances to financial advisors and other employees	23,611	18,995
Amortization of premium on investment portfolio	3,830	1,622
Provision for loan losses and allowance for loans and advances to financial advisors and other employees	6,259	4,571
Amortization of intangible assets	2,981	2,974
Deferred income taxes	19,873	72,979
Tax deficit from stock-based compensation		4,215
Stock-based compensation	27,915	30,450
(Gains)/losses on sale of investments	(2,459)	3,826
Other, net	999	(2,524)
Decrease/(increase) in operating assets, net of assets acquired:
Cash segregated for regulatory purposes and restricted cash	73,021	190,676
Receivables:
Brokerage clients	83,353	216,856
Brokers, dealers, and clearing organizations	469,038	(117,959)
Securities purchased under agreements to resell	(70,260)	(47,523)
Financial instruments owned, including those pledged	(131,791)	(279,338)
Loans originated as held for sale	(349,044)	(419,601)
Proceeds from mortgages held for sale	361,435	472,886
Loans and advances to financial advisors and other employees	(21,873)	(25,417)
Other assets	(87,104)	(133,412)
Increase/(decrease) in operating liabilities, net of liabilities assumed:
Brokerage clients	(96,616)	76,992
Brokers, dealers, and clearing organizations	74,655	(3,792)
Drafts	(11,022)	(109,354)
Financial instruments sold, but not yet purchased	55,426	153,097
Other liabilities and accrued expenses	(170,766)	(210,511)
Net cash provided by/(used in) operating activities	335,995	(61,608)
Cash Flows From Investing Activities:
Maturities and principal paydowns of available-for-sale securities	198,407	31,303
Calls and principal paydowns of held-to-maturity securities	67,473	37,577
Sale or maturity of investments	2,411	12,978
Increase in bank loans, net	(269,337)	(327,931)
Payments for:
Purchase of available-for-sale securities	(391,585)	(529,707)
Purchase of held-to-maturity securities	(219,500)	(210,677)
Purchase of investments	(150)	(1,313)
Purchase of fixed assets	(8,014)	(9,270)
Acquisitions, net of cash received	(9,070)	(68,680)
Net cash used in investing activities	(629,365)	(1,065,720)
Cash Flows From Financing Activities:
Proceeds from/(repayments of) short-term borrowings, net	(178,000)	238,497
Proceeds from Federal Home Loan Bank advances, net	290,000	352,000
Payment of contingent consideration	(8,356)
(Decrease)/increase in securities sold under agreements to repurchase	(48,819)	12,055
Increase in bank deposits, net	173,478	579,744
Decrease in securities loaned	(106,474)	(151,319)
Tax deficit from stock-based compensation		(4,215)
Restricted stock conversions	(82,954)	(35,976)
Proceeds from stock option exercises		175
Repurchase of common stock		(95,116)
Cash dividends on preferred stock	(2,344)
Net cash provided by financing activities	36,531	895,845
Effect of exchange rate changes on cash	2,294	(2,186)
Decrease in cash and cash equivalents	(254,545)	(233,669)
Cash and cash equivalents at beginning of period	912,932	811,019
Cash and cash equivalents at end of period	658,387	577,350
Supplemental disclosure of cash flow information:
Cash paid for income taxes, net of refunds	3,573	20,061
Cash paid for interest	16,093	13,630
Noncash financing activities:
Unit grants, net of forfeitures	35,273	98,876
Issuance of common stock for acquisitions	$ 9,352	$ 11,427