Fair Value Accounting (Carrying And Estimated Fair Values Of Financial Instruments Carried On Balance Sheet) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	$ 352,060	$ 367,092
Interest bearing funds with Federal Reserve Bank	908,527	829,887
Interest earning deposits with banks	21,686	17,387
Federal funds sold and securities purchased under resale agreements	76,300	69,819
Trading account assets	4,801	5,097
Mortgage loans held for sale	62,867	59,275
Investment securities available for sale	3,582,244	3,587,818
Loans, net	22,503,687	22,177,069
Non-interest bearing deposits	6,896,547	6,732,970
Federal funds purchased and securities sold under repurchase agreements	203,979	177,025
Long-term debt	2,360,865	2,186,893
Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	352,060	367,092
Interest bearing funds with Federal Reserve Bank	908,527	829,887
Interest earning deposits with banks	21,686	17,387
Federal funds sold and securities purchased under resale agreements	76,300	$ 69,819
Trading account assets	15
Mortgage loans held for sale	0
Other loans held for sale		$ 0
Investment securities available for sale	55,044	56,102
Private equity investments	0	0
Mutual funds held in Rabbi Trusts	11,035	10,664
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	203,979	177,025
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
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	4,786	5,097
Mortgage loans held for sale	62,867	59,275
Other loans held for sale		0
Investment securities available for sale	3,525,562	3,529,971
Private equity investments	750	870
Mutual funds held in Rabbi Trusts	0	0
Loans, net	0	0
Derivative asset positions	35,958	27,139
Trading account liabilities	1,573	1,032
Non-interest bearing deposits	6,896,547	6,732,970
Interest bearing deposits	16,559,165	16,516,222
Federal funds purchased and securities sold under repurchase agreements	0	0
Long-term debt	2,458,126	2,244,376
Derivative liability positions	34,994	26,030
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		425
Investment securities available for sale	1,638	1,745
Private equity investments	26,757	27,148
Mutual funds held in Rabbi Trusts	0	0
Loans, net	22,480,492	22,192,903
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
Long-term debt	0	0
Derivative liability positions	1,415	1,415
Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	352,060	367,092
Interest bearing funds with Federal Reserve Bank	908,527	829,887
Interest earning deposits with banks	21,686	17,387
Federal funds sold and securities purchased under resale agreements	76,300	69,819
Trading account assets	4,801	5,097
Mortgage loans held for sale	62,867	59,275
Other loans held for sale		425
Investment securities available for sale	3,582,244	3,587,818
Private equity investments	27,507	28,018
Mutual funds held in Rabbi Trusts	11,035	10,664
Loans, net	22,758,203	22,429,565
Derivative asset positions	35,958	27,139
Trading account liabilities	1,573	1,032
Non-interest bearing deposits	6,896,547	6,732,970
Interest bearing deposits	16,553,381	16,509,691
Federal funds purchased and securities sold under repurchase agreements	203,979	177,025
Long-term debt	2,360,865	2,186,893
Derivative liability positions	36,409	27,445
Estimated Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	352,060	367,092
Interest bearing funds with Federal Reserve Bank	908,527	829,887
Interest earning deposits with banks	21,686	17,387
Federal funds sold and securities purchased under resale agreements	76,300	69,819
Trading account assets	4,801	5,097
Mortgage loans held for sale	62,867	59,275
Other loans held for sale		425
Investment securities available for sale	3,582,244	3,587,818
Private equity investments	27,507	28,018
Mutual funds held in Rabbi Trusts	11,035	10,664
Loans, net	22,480,492	22,192,903
Derivative asset positions	35,958	27,139
Trading account liabilities	1,573	1,032
Non-interest bearing deposits	6,896,547	6,732,970
Interest bearing deposits	16,559,165	16,516,222
Federal funds purchased and securities sold under repurchase agreements	203,979	177,025
Long-term debt	2,458,126	2,244,376
Derivative liability positions	$ 36,409	$ 27,445

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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No definition available.

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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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No definition available.

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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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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. 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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No definition available.

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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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