Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
CASH FLOWS FROM OPERATING ACTIVITIES
Net income for the period	$ 92,025us-gaap_ProfitLoss	$ 101,210us-gaap_ProfitLoss
Adjustments to reconcile net income to net cash provided by operating activities:
Net impairment losses on investment securities	0us-gaap_AssetImpairmentCharges	27us-gaap_AssetImpairmentCharges
Provision for credit losses	(283)	(1,622)
Depreciation and amortization	34,169us-gaap_DepreciationAndAmortization	32,404us-gaap_DepreciationAndAmortization
Fixed income securities losses (gains), net	239	(30,914)
Deferred income tax expense (benefit)	3,402us-gaap_DeferredIncomeTaxExpenseBenefit	78,278us-gaap_DeferredIncomeTaxExpenseBenefit
Net decrease (increase) in trading securities	(1,021)	(21,862)
Net decrease in loans held for sale	3,517	44,984
Change in other liabilities	25,566	(77,796)
Change in other assets	(65,248)	3,226
Other, net	(3,549)us-gaap_OtherNoncashIncomeExpense	2,336us-gaap_OtherNoncashIncomeExpense
Net cash provided by operating activities	88,817	130,271
CASH FLOWS FROM INVESTING ACTIVITIES
Net decrease (increase) in money market investments	253,274	(80,851)
Proceeds from maturities and paydowns of investment securities held-to-maturity	39,323	18,935
Purchases of investment securities held-to-maturity	(22,576)	(35,750)
Proceeds from sales, maturities, and paydowns of investment securities available-for-sale	228,894	847,288
Purchases of investment securities available-for-sale	(784,856)	(452,123)
Change in loans and leases	100,442	166,415
Net purchases of premises and equipment	(33,533)	(76,916)
Proceeds from sales of other real estate owned	3,401	11,825
Other, net	3,351	5,617
Net cash provided by (used in) investing activities	(413,164)	71,610
CASH FLOWS FROM FINANCING ACTIVITIES
Net increase (decrease) in deposits	275,285us-gaap_IncreaseDecreaseInDeposits	170,422us-gaap_IncreaseDecreaseInDeposits
Net change in short-term funds borrowed	(40,626)	(60,511)
Repayments of long-term debt	(8,185)us-gaap_RepaymentsOfLongTermDebt	(124,755)us-gaap_RepaymentsOfLongTermDebt
Proceeds from issuances of common stock	962	2,880
Dividends paid on common and preferred stock	(23,234)us-gaap_PaymentsOfDividends	(23,741)us-gaap_PaymentsOfDividends
Other, net	(939)	(303)
Net cash provided by (used in) financing activities	203,263	(36,008)
Net increase (decrease) in cash and due from banks	(121,084)	165,873
Cash and due from banks at beginning of period	841,942us-gaap_CashAndDueFromBanks	1,173,057us-gaap_CashAndDueFromBanks
Cash and due from banks at end of period	720,858us-gaap_CashAndDueFromBanks	1,338,930us-gaap_CashAndDueFromBanks
Cash paid for interest	22,119us-gaap_InterestPaid	40,849us-gaap_InterestPaid
Net cash paid for income taxes	$ (500)us-gaap_IncomeTaxesPaidNet	$ (81)us-gaap_IncomeTaxesPaidNet

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