Fair Value Of Financial Instruments (Schedule Of Estimated Fair Value Of Financial Instruments) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans held for sale	$ 6,500
Securities purchased under agreements to resell	700,000	$ 700,000
Interest earning deposits with banks	134,697	30,631
Cash and due from banks	423,048	438,439
Derivative Assets	5,092	8,349
Assets held in trust for deferred compensation plan	13,582	12,843
Non-interest bearing deposits	6,953,430	7,158,962
Savings, interest checking and money market deposits	11,828,138	11,499,620
Other Borrowings	9,214	1,758
Derivative Liabilities	16,373	8,074
Liabilities held in trust for deferred compensation plan	13,582	12,843
Fair Value Hierarchy, Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative Assets	0	0
Assets held in trust for deferred compensation plan	13,582	12,843
Derivative Liabilities	0	0
Liabilities held in trust for deferred compensation plan	13,582	12,843
Fair Value Hierarchy, Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative Assets	4,481	7,723
Assets held in trust for deferred compensation plan	0	0
Derivative Liabilities	16,282	7,951
Liabilities held in trust for deferred compensation plan	0	0
Fair Value Hierarchy, Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative Assets	611	626
Assets held in trust for deferred compensation plan	0	0
Derivative Liabilities	91	123
Liabilities held in trust for deferred compensation plan	0	0
Carrying (Reported) Amount, Fair Value Disclosure [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	13,893,361	13,983,674
Loans held for sale	16,435	21,398
Investments, Fair Value Disclosure	8,624,037	8,893,307
Federal funds sold	17,000	42,775
Securities purchased under agreements to resell	700,000	700,000
Interest earning deposits with banks	134,697	30,631
Cash and due from banks	423,048	438,439
Derivative Assets	5,092	8,349
Assets held in trust for deferred compensation plan	13,582	12,843
Assets, Fair Value Disclosure	23,827,252	24,131,416
Non-interest bearing deposits	6,953,430	7,158,962
Savings, interest checking and money market deposits	11,828,138	11,499,620
Time open and certificates of deposits	1,756,903	1,766,864
Federal Funds Purchased, Fair Value Disclosure	104,940	202,370
SecuritiesSold under Agreements to Repurchase, Fair Value Disclosure	1,027,389	1,304,768
Other Borrowings	9,214	1,758
Derivative Liabilities	16,373	8,074
Liabilities held in trust for deferred compensation plan	13,582	12,843
Financial Liabilities Fair Value Disclosure	21,709,969	21,955,259
Carrying (Reported) Amount, Fair Value Disclosure [Member] \| Business [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	4,960,614	4,958,554
Carrying (Reported) Amount, Fair Value Disclosure [Member] \| Real Estate - Construction And Land [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	932,058	968,820
Carrying (Reported) Amount, Fair Value Disclosure [Member] \| Real Estate - Business [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	2,724,584	2,697,452
Carrying (Reported) Amount, Fair Value Disclosure [Member] \| Real Estate - Personal [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	2,069,012	2,062,787
Carrying (Reported) Amount, Fair Value Disclosure [Member] \| Consumer [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	2,069,235	2,104,487
Carrying (Reported) Amount, Fair Value Disclosure [Member] \| Revolving Home Equity [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	382,825	400,587
Carrying (Reported) Amount, Fair Value Disclosure [Member] \| Credit Card [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	752,651	783,864
Carrying (Reported) Amount, Fair Value Disclosure [Member] \| Overdrafts [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	2,382	7,123
Estimate of Fair Value, Fair Value Disclosure [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	13,601,017	13,993,509
Loans held for sale	16,435	21,398
Investments, Fair Value Disclosure	8,624,037	8,893,307
Federal funds sold	17,000	42,775
Securities purchased under agreements to resell	685,539	695,194
Interest earning deposits with banks	134,697	30,631
Cash and due from banks	423,048	438,439
Derivative Assets	5,092	8,349
Assets held in trust for deferred compensation plan	13,582	12,843
Assets, Fair Value Disclosure	23,520,447	24,136,445
Non-interest bearing deposits	6,953,430	7,158,962
Savings, interest checking and money market deposits	11,828,138	11,499,620
Time open and certificates of deposits	1,755,581	1,768,780
Federal Funds Purchased, Fair Value Disclosure	104,940	202,370
SecuritiesSold under Agreements to Repurchase, Fair Value Disclosure	1,027,814	1,305,375
Other Borrowings	9,214	1,758
Derivative Liabilities	16,373	8,074
Liabilities held in trust for deferred compensation plan	13,582	12,843
Financial Liabilities Fair Value Disclosure	21,709,072	21,957,782
Estimate of Fair Value, Fair Value Disclosure [Member] \| Business [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	4,861,150	4,971,401
Estimate of Fair Value, Fair Value Disclosure [Member] \| Real Estate - Construction And Land [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	927,316	979,389
Estimate of Fair Value, Fair Value Disclosure [Member] \| Real Estate - Business [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	2,690,305	2,702,598
Estimate of Fair Value, Fair Value Disclosure [Member] \| Real Estate - Personal [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	2,009,625	2,060,443
Estimate of Fair Value, Fair Value Disclosure [Member] \| Consumer [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	2,032,968	2,074,129
Estimate of Fair Value, Fair Value Disclosure [Member] \| Revolving Home Equity [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	376,043	400,333
Estimate of Fair Value, Fair Value Disclosure [Member] \| Credit Card [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	701,833	798,093
Estimate of Fair Value, Fair Value Disclosure [Member] \| Overdrafts [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	1,777	7,123
Estimate of Fair Value, Fair Value Disclosure [Member] \| Fair Value Hierarchy, Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	0	0
Loans held for sale	0	0
Investments, Fair Value Disclosure	932,074	937,011
Federal funds sold	17,000	42,775
Securities purchased under agreements to resell	0	0
Interest earning deposits with banks	134,697	30,631
Cash and due from banks	423,048	438,439
Derivative Assets	0	0
Assets held in trust for deferred compensation plan	13,582	12,843
Assets, Fair Value Disclosure	1,520,401	1,461,699
Non-interest bearing deposits	6,953,430	7,158,962
Savings, interest checking and money market deposits	11,828,138	11,499,620
Time open and certificates of deposits	0	0
Federal Funds Purchased, Fair Value Disclosure	104,940	202,370
SecuritiesSold under Agreements to Repurchase, Fair Value Disclosure	0	0
Other Borrowings	0	0
Derivative Liabilities	0	0
Liabilities held in trust for deferred compensation plan	13,582	12,843
Financial Liabilities Fair Value Disclosure	18,900,090	18,873,795
Estimate of Fair Value, Fair Value Disclosure [Member] \| Fair Value Hierarchy, Level 1 [Member] \| Business [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	0	0
Estimate of Fair Value, Fair Value Disclosure [Member] \| Fair Value Hierarchy, Level 1 [Member] \| Real Estate - Construction And Land [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	0	0
Estimate of Fair Value, Fair Value Disclosure [Member] \| Fair Value Hierarchy, Level 1 [Member] \| Real Estate - Business [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	0	0
Estimate of Fair Value, Fair Value Disclosure [Member] \| Fair Value Hierarchy, Level 1 [Member] \| Real Estate - Personal [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	0	0
Estimate of Fair Value, Fair Value Disclosure [Member] \| Fair Value Hierarchy, Level 1 [Member] \| Consumer [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	0	0
Estimate of Fair Value, Fair Value Disclosure [Member] \| Fair Value Hierarchy, Level 1 [Member] \| Revolving Home Equity [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	0	0
Estimate of Fair Value, Fair Value Disclosure [Member] \| Fair Value Hierarchy, Level 1 [Member] \| Credit Card [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	0	0
Estimate of Fair Value, Fair Value Disclosure [Member] \| Fair Value Hierarchy, Level 1 [Member] \| Overdrafts [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	0	0
Estimate of Fair Value, Fair Value Disclosure [Member] \| Fair Value Hierarchy, Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	0	0
Loans held for sale	16,435	21,398
Investments, Fair Value Disclosure	7,564,757	7,838,522
Federal funds sold	0	0
Securities purchased under agreements to resell	0	0
Interest earning deposits with banks	0	0
Cash and due from banks	0	0
Derivative Assets	4,481	7,723
Assets held in trust for deferred compensation plan	0	0
Assets, Fair Value Disclosure	7,585,673	7,867,643
Non-interest bearing deposits	0	0
Savings, interest checking and money market deposits	0	0
Time open and certificates of deposits	0	0
Federal Funds Purchased, Fair Value Disclosure	0	0
SecuritiesSold under Agreements to Repurchase, Fair Value Disclosure	0	0
Other Borrowings	7,530	0
Derivative Liabilities	16,282	7,951
Liabilities held in trust for deferred compensation plan	0	0
Financial Liabilities Fair Value Disclosure	23,812	7,951
Estimate of Fair Value, Fair Value Disclosure [Member] \| Fair Value Hierarchy, Level 2 [Member] \| Business [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	0	0
Estimate of Fair Value, Fair Value Disclosure [Member] \| Fair Value Hierarchy, Level 2 [Member] \| Real Estate - Construction And Land [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	0	0
Estimate of Fair Value, Fair Value Disclosure [Member] \| Fair Value Hierarchy, Level 2 [Member] \| Real Estate - Business [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	0	0
Estimate of Fair Value, Fair Value Disclosure [Member] \| Fair Value Hierarchy, Level 2 [Member] \| Real Estate - Personal [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	0	0
Estimate of Fair Value, Fair Value Disclosure [Member] \| Fair Value Hierarchy, Level 2 [Member] \| Consumer [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	0	0
Estimate of Fair Value, Fair Value Disclosure [Member] \| Fair Value Hierarchy, Level 2 [Member] \| Revolving Home Equity [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	0	0
Estimate of Fair Value, Fair Value Disclosure [Member] \| Fair Value Hierarchy, Level 2 [Member] \| Credit Card [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	0	0
Estimate of Fair Value, Fair Value Disclosure [Member] \| Fair Value Hierarchy, Level 2 [Member] \| Overdrafts [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	0	0
Estimate of Fair Value, Fair Value Disclosure [Member] \| Fair Value Hierarchy, Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	13,601,017	13,993,509
Loans held for sale	0	0
Investments, Fair Value Disclosure	127,206	117,774
Federal funds sold	0	0
Securities purchased under agreements to resell	685,539	695,194
Interest earning deposits with banks	0	0
Cash and due from banks	0	0
Derivative Assets	611	626
Assets held in trust for deferred compensation plan	0	0
Assets, Fair Value Disclosure	14,414,373	14,807,103
Non-interest bearing deposits	0	0
Savings, interest checking and money market deposits	0	0
Time open and certificates of deposits	1,755,581	1,768,780
Federal Funds Purchased, Fair Value Disclosure	0	0
SecuritiesSold under Agreements to Repurchase, Fair Value Disclosure	1,027,814	1,305,375
Other Borrowings	1,684	1,758
Derivative Liabilities	91	123
Liabilities held in trust for deferred compensation plan	0	0
Financial Liabilities Fair Value Disclosure	2,785,170	3,076,036
Estimate of Fair Value, Fair Value Disclosure [Member] \| Fair Value Hierarchy, Level 3 [Member] \| Business [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	4,861,150	4,971,401
Estimate of Fair Value, Fair Value Disclosure [Member] \| Fair Value Hierarchy, Level 3 [Member] \| Real Estate - Construction And Land [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	927,316	979,389
Estimate of Fair Value, Fair Value Disclosure [Member] \| Fair Value Hierarchy, Level 3 [Member] \| Real Estate - Business [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	2,690,305	2,702,598
Estimate of Fair Value, Fair Value Disclosure [Member] \| Fair Value Hierarchy, Level 3 [Member] \| Real Estate - Personal [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	2,009,625	2,060,443
Estimate of Fair Value, Fair Value Disclosure [Member] \| Fair Value Hierarchy, Level 3 [Member] \| Consumer [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	2,032,968	2,074,129
Estimate of Fair Value, Fair Value Disclosure [Member] \| Fair Value Hierarchy, Level 3 [Member] \| Revolving Home Equity [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	376,043	400,333
Estimate of Fair Value, Fair Value Disclosure [Member] \| Fair Value Hierarchy, Level 3 [Member] \| Credit Card [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	701,833	798,093
Estimate of Fair Value, Fair Value Disclosure [Member] \| Fair Value Hierarchy, Level 3 [Member] \| Overdrafts [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	$ 1,777	$ 7,123

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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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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Aggregate carrying value as of the balance sheet date of the liabilities for all deferred compensation arrangements. Represents currently earned compensation under compensation arrangements that is not actually paid until a later date.

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Carrying amount as of the balance sheet date of assets held under deferred compensation agreements.

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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, after the 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 not subject to a master netting arrangement and not elected to be offset.

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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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Fair value portion of short term borrowing where a bank borrows, at the federal funds rate, from another bank.

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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.

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Fair value of financial obligations, including, but not limited to, debt instruments, derivative liabilities, federal funds purchased and sold under agreements to repurchase, securities loaned or sold under agreements to repurchase, financial instruments sold not yet purchased, guarantees, line of credit, loans and notes payable, servicing liability, and trading liabilities.

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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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Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

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