CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Operating Activities
Net income	$ 26,307	$ 28,196
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses	1,705	3,407
Depreciation, amortization and accretion, net	(1,031)	(11,830)
Net realized gains on securities		(46)
Deferred income taxes	1,531	494
Other, net	1,990	8,320
Net change in securities purchased under agreements to resell	(23,798)	9,014
Net change in assets segregated for regulatory purposes	14,598	37,899
Net change in trading securities	(107,766)	(154,279)
Net change in broker-dealer and clearing organization receivables	(39,422)	130,858
Net change in FDIC indemnification asset	19,424	11,214
Net change in other assets	(8,702)	(50,550)
Net change in broker-dealer and clearing organization payables	110,694	(162,722)
Net change in other liabilities	(104,858)	(48,283)
Net change in securities sold, not yet purchased	(9,696)	35,660
Proceeds from sale of mortgage servicing rights asset	17,499
Net gains from sales of loans	(124,150)	(127,297)
Loans originated for sale	(2,939,349)	(3,052,579)
Proceeds from loans sold	3,514,340	3,352,409
Net cash provided by operating activities	349,316	9,885
Investing Activities
Proceeds from maturities and principal reductions of securities held to maturity	15,152	21,398
Proceeds from sales, maturities and principal reductions of securities available for sale	83,048	64,918
Purchases of securities held to maturity	(831)
Purchases of securities available for sale	(240,757)	(51,531)
Net change in loans	57,902	(233,309)
Purchases of premises and equipment and other assets	(4,951)	(9,948)
Proceeds from sales of premises and equipment and other real estate owned	11,438	22,068
Net cash paid for Federal Home Loan Bank and Federal Reserve Bank stock	34,953	12,311
Net cash used in investing activities	(44,046)	(174,093)
Financing Activities
Net change in deposits	245,777	139,925
Net change in short-term borrowings	(663,512)	(114,452)
Proceeds from notes payable	72,382	5,553
Payments on notes payable	(65,573)	(12,028)
Proceeds from issuance of common stock		3,850
Payments to repurchase common stock	(7,205)
Dividends paid on common stock	(5,802)
Net cash distributed to noncontrolling interest	(575)	(437)
Taxes paid on employee stock awards netting activity	(838)	(33)
Other, net	(356)	(106)
Net cash provided by (used in) financing activities	(425,702)	22,272
Net change in cash and cash equivalents	(120,432)	(141,936)
Cash and cash equivalents, beginning of period	690,764	669,445
Cash and cash equivalents, end of period	570,332	527,509
Supplemental Disclosures of Cash Flow Information
Cash paid for interest	14,407	16,377
Cash paid for income taxes, net of refunds	1,262	831
Supplemental Schedule of Non-Cash Activities
Conversion of loans to other real estate owned	1,945	4,726
Additions to mortgage servicing rights	$ 1,224	$ 1,639