Fair Values Of Assets And Liabilities (Summary Of Balances Of Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) (USD $)	Sep. 30, 2011	Dec. 31, 2010	Sep. 30, 2010
Available-for-sale securities	$ 1,267,682,000	$ 1,496,302,000	$ 1,324,179,000
Aggregate fair value of mortgage loans held-for-sale	204,081,000	356,662,000	307,231,000
Trading account securities	297,000		4,935,000
Mortgage loans held-for-sale	204,081,000		307,231,000
Mortgage servicing rights	6,740,000		5,179,000
Nonqualified deferred compensation assets	4,289,000		3,211,000
Derivative assets	39,803,000		24,722,000
Assets, Total	1,522,892,000		1,669,457,000
Derivative Liabilities	50,612,000		38,982,000
Loans past due greater than 90 days and still accruing	0		0
U.S. Treasury [Member]
Available-for-sale securities	16,203,000	96,097,000	2,015,000
U.S. Treasury [Member] \| Level 2 [Member]
Available-for-sale securities	16,203,000		2,015,000
U.S. Government Agencies [Member]
Available-for-sale securities	686,956,000	884,055,000	874,327,000
U.S. Government Agencies [Member] \| Level 2 [Member]
Available-for-sale securities	678,997,000		874,327,000
U.S. Government Agencies [Member] \| Level 3 [Member]
Available-for-sale securities	7,959,000
Municipal Securities [Member]
Available-for-sale securities	62,307,000	52,303,000	54,641,000
Municipal Securities [Member] \| Level 2 [Member]
Available-for-sale securities	36,902,000		38,716,000
Municipal Securities [Member] \| Level 3 [Member]
Available-for-sale securities	25,405,000		15,925,000
Corporate Notes And Other [Member]
Available-for-sale securities	186,637,000		173,003,000
Corporate Notes And Other [Member] \| Level 2 [Member]
Available-for-sale securities	180,728,000		167,511,000
Corporate Notes And Other [Member] \| Level 3 [Member]
Available-for-sale securities	5,909,000		5,492,000
Mortgage-Backed [Member]
Available-for-sale securities	272,547,000	161,681,000	180,361,000
Mortgage-Backed [Member] \| Level 2 [Member]
Available-for-sale securities	269,595,000		177,034,000
Mortgage-Backed [Member] \| Level 3 [Member]
Available-for-sale securities	2,952,000		3,327,000
Equity Securities [Member]
Available-for-sale securities	43,032,000		39,832,000
Equity Securities [Member] \| Level 2 [Member]
Available-for-sale securities	12,141,000		11,566,000
Equity Securities [Member] \| Level 3 [Member]
Available-for-sale securities	30,891,000		28,266,000
Level 1 [Member]
Trading account securities			58,000
Assets, Total			58,000
Level 2 [Member]
Trading account securities	272,000		786,000
Mortgage loans held-for-sale	204,081,000		307,231,000
Nonqualified deferred compensation assets	4,289,000		3,211,000
Derivative assets	39,803,000		24,722,000
Assets, Total	1,443,011,000		1,607,119,000
Derivative Liabilities	50,612,000		38,982,000
Level 3 [Member]
Trading account securities	25,000		4,091,000
Mortgage servicing rights	6,740,000		5,179,000
Assets, Total	79,881,000		62,280,000
Fair Value [Member]
Remaining contractual principal balance outstanding, mortgage loans held-for-sale	$ 200,400,000		$ 297,200,000

This element represents the aggregate of the assets reported on the balance sheet at period end measured at fair value on a recurring basis by the entity. This element is intended to be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements.

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- Definition

For an unclassified balance sheet, this item represents investments in debt and equity securities which are categorized neither as held-to-maturity nor trading.

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- Definition

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

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- Definition

Fair value as of the balance sheet date of the gross assets less the gross liabilities of a derivative asset or group of derivative assets.

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Fair value as of the balance sheet date of the gross assets less the gross liabilities of a derivative liability or group of derivative liabilities.

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- Definition

Financing receivables that are equal to or greater than 90 days past due.

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- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents loans held-for-sale as presented on the statement of financial position which may include mortgage loans held-for-sale, finance receivables held-for-sale, or any other loans classified as held-for-sale which are due the Company as of the balance sheet date.

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- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents mortgage loans held-for-sale as presented on the statement of financial position which are due the Company as of the balance sheet date.

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- Definition

This is the principal amount outstanding for loans which are in the process of being securitized as of the date of the statement of financial position (across all types of loans).

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- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents marketable and other securities categorized as trading securities as of the balance sheet date.

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- Definition

Fair value of mortgage servicing rights

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