Fair Value Accounting (Carrying And Estimated Fair Values Of Financial Instruments Carried On Balance Sheet) (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	$ 329,396	$ 485,489
Interest bearing funds with Federal Reserve Bank	837,641	721,362
Interest earning deposits with banks	21,170	11,810
Federal funds sold and securities purchased under resale agreements	69,732	73,111
Trading account assets	5,844	13,863
Mortgage loans held for sale	73,623	63,328
Investment securities available for sale	3,487,332	3,041,406
Loans, net	21,613,409	20,836,382
Non-interest bearing deposits	6,570,227	6,228,472
Federal funds purchased and securities sold under repurchase agreements	135,475	126,916
Long-term debt	2,038,719	2,140,319
Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	329,396	485,489
Interest bearing funds with Federal Reserve Bank	837,641	721,362
Interest earning deposits with banks	21,170	11,810
Federal funds sold and securities purchased under resale agreements	69,732	73,111
Trading account assets	0	0
Mortgage loans held for sale	0	0
Other loans held for sale		0
Investment securities available for sale	55,235	51,609
Private equity investments	0	0
Mutual funds held in Rabbi Trusts	10,233	11,252
Loans, net	0	0
Derivative asset positions	0	0
Trading account liabilities	0	0
Non-interest bearing deposits	0	0
Interest bearing deposits	0	0
Federal funds purchased and securities sold under repurchase agreements	135,475	126,916
Salary stock units		1,206
Long-term debt	0	0
Derivative liability positions	0	0
Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	0	0
Interest bearing funds with Federal Reserve Bank	0	0
Interest earning deposits with banks	0	0
Federal funds sold and securities purchased under resale agreements	0	0
Trading account assets	5,844	13,863
Mortgage loans held for sale	73,623	63,328
Other loans held for sale		0
Investment securities available for sale	3,430,566	2,988,152
Private equity investments	867	995
Mutual funds held in Rabbi Trusts	0	0
Loans, net	0	0
Derivative asset positions	34,555	32,117
Trading account liabilities	3,002	2,100
Non-interest bearing deposits	6,570,227	6,228,472
Interest bearing deposits	16,218,720	15,299,372
Federal funds purchased and securities sold under repurchase agreements	0	0
Salary stock units		0
Long-term debt	2,098,864	2,191,279
Derivative liability positions	34,268	32,151
Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	0	0
Interest bearing funds with Federal Reserve Bank	0	0
Interest earning deposits with banks	0	0
Federal funds sold and securities purchased under resale agreements	0	0
Trading account assets	0	0
Mortgage loans held for sale	0	0
Other loans held for sale		3,606
Investment securities available for sale	1,531	1,645
Private equity investments	26,850	27,367
Mutual funds held in Rabbi Trusts	0	0
Loans, net	21,677,842	20,872,939
Derivative asset positions	0	0
Trading account liabilities	0	0
Non-interest bearing deposits	0	0
Interest bearing deposits	0	0
Federal funds purchased and securities sold under repurchase agreements	0	0
Salary stock units		0
Long-term debt	0	0
Derivative liability positions	1,415	1,401
Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	329,396	485,489
Interest bearing funds with Federal Reserve Bank	837,641	721,362
Interest earning deposits with banks	21,170	11,810
Federal funds sold and securities purchased under resale agreements	69,732	73,111
Trading account assets	5,844	13,863
Mortgage loans held for sale	73,623	63,328
Other loans held for sale		3,606
Investment securities available for sale	3,487,332	3,041,406
Private equity investments	27,717	28,362
Mutual funds held in Rabbi Trusts	10,233	11,252
Loans, net	21,864,309	21,097,699
Derivative asset positions	34,555	32,117
Trading account liabilities	3,002	2,100
Non-interest bearing deposits	6,570,227	6,228,472
Interest bearing deposits	16,207,186	15,303,228
Federal funds purchased and securities sold under repurchase agreements	135,475	126,916
Salary stock units		1,206
Long-term debt	2,038,719	2,140,319
Derivative liability positions	35,683	33,553
Estimated Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	329,396	485,489
Interest bearing funds with Federal Reserve Bank	837,641	721,362
Interest earning deposits with banks	21,170	11,810
Federal funds sold and securities purchased under resale agreements	69,732	73,111
Trading account assets	5,844	13,863
Mortgage loans held for sale	73,623	63,328
Other loans held for sale		3,606
Investment securities available for sale	3,487,332	3,041,406
Private equity investments	27,717	28,362
Mutual funds held in Rabbi Trusts	10,233	11,252
Loans, net	21,677,842	20,872,939
Derivative asset positions	34,555	32,117
Trading account liabilities	3,002	2,100
Non-interest bearing deposits	6,570,227	6,228,472
Interest bearing deposits	16,218,720	15,299,372
Federal funds purchased and securities sold under repurchase agreements	135,475	126,916
Salary stock units		1,206
Long-term debt	2,098,864	2,191,279
Derivative liability positions	$ 35,683	$ 33,553

Federal funds purchased, repurchase agreements, and other short-term borrowings

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Interest bearing funds deposited with the Federal Reserve Bank.

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Mutual funds held In Rabbi Trusts.

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Private Equity Investments

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Salary Stock Units, Amount

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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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For banks and other depository institutions: Includes cash on hand (currency and coin), cash items in process of collection, noninterest bearing deposits due from other financial institutions (including corporate credit unions), and noninterest bearing balances with the Federal Reserve Banks, Federal Home Loan Banks and central banks.

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Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

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Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Includes: (1) the amount outstanding of funds lent to other depository institutions, securities brokers, or securities dealers in the form of Federal Funds sold; for example, immediately available funds lent under agreements or contracts that mature in one business day or roll over under a continuing contract, regardless of the nature of the transaction or the collateral involved, excluding overnight lending for commercial and industrial purposes. Also include Federal Funds sold under agreements to resell on a gross basis, excluding (1) sales of term Federal Funds, (2) due bills representing purchases of securities or other assets by the reporting bank that have not yet been delivered and similar instruments, (3) resale agreements that mature in more than one business day involving assets other than securities, and (4) yield maintenance dollar repurchase agreements (Federal Funds Sold) and (2) the dollar amount outstanding of funds lent in the form of security resale agreements regardless of maturity, if the agreement requires the bank to resell the identical security purchased or a security that meets the definition of substantially the same in the case of a dollar roll. Also include purchases of participations in pools of securities, regardless of maturity (Securities Purchased Under Agreements to Re-sell).

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The aggregate of all domestic and foreign interest-bearing deposit liabilities.

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For banks and other depository institutions (including Federal Reserve Banks, if applicable): Interest-bearing deposits in other financial institutions for relatively short periods of time including, for example, certificates of deposits, which are presented separately from cash on the balance sheet.

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Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements and loans held for sale.

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Amount, after allowance for bad debt, of mortgage loan receivables held-for-sale that are not part of a disposal group. Excludes loans and leases covered under loss sharing agreements and loans classified as debt securities.

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Amount, after allowance for bad debt, of other loan receivables held-for-sale that are not part of a disposal group. Excludes loans and leases covered under loss sharing agreements and loans classified as debt securities.

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Carrying amount of long-term debt, net of unamortized discount or premium, including current and noncurrent amounts. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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The aggregate amount of all domestic and foreign noninterest-bearing deposits liabilities held by the entity.

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The carrying amount of liabilities as of the balance sheet date that pertain to principal and customer trading transactions, or which may be incurred with the objective of generating a profit from short-term fluctuations in price as part of an entity's market-making, hedging and proprietary trading. Examples include short positions in securities, derivatives and commodities, obligations under repurchase agreements, and securities borrowed arrangements.

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Amount of investments in debt and equity securities and other forms of securities that provide ownership interests classified as trading.

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