Fair Value of Financial Instruments, Part 2 (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012	Dec. 31, 2011
Financial assets [Abstract]
Cash and cash equivalents	$ 555,649	$ 544,016	$ 442,644	$ 532,943
Securities available for sale	908,446	912,092
Held to maturity securities	95,968	151,126
Net loans	2,804,692	2,771,705
Accrued interest receivable	11,700	11,752
Financial liabilities [Abstract]
Demand deposits	314,660	300,544
Interest bearing deposits	3,579,883	3,505,833
Short-term borrowings	185,226	159,846
Accrued interest payable	438	449
Level 1 [Member]
Financial assets [Abstract]
Cash and cash equivalents	555,649	544,016
Securities available for sale	10	10
Held to maturity securities	0	0
Net loans	0	0
Accrued interest receivable	0	0
Financial liabilities [Abstract]
Demand deposits	314,660	300,544
Interest bearing deposits	2,464,069	2,426,170
Short-term borrowings	0	0
Accrued interest payable	96	103
Level 2 [Member]
Financial assets [Abstract]
Cash and cash equivalents	0	0
Securities available for sale	908,436	912,082
Held to maturity securities	95,968	151,126
Net loans	0	0
Accrued interest receivable	3,803	4,114
Financial liabilities [Abstract]
Demand deposits	0	0
Interest bearing deposits	1,115,814	1,079,663
Short-term borrowings	185,226	159,846
Accrued interest payable	342	346
Level 3 [Member]
Financial assets [Abstract]
Cash and cash equivalents	0	0
Securities available for sale	0	0
Held to maturity securities	0	0
Net loans	2,804,692	2,771,705
Accrued interest receivable	7,897	7,638
Financial liabilities [Abstract]
Demand deposits	0	0
Interest bearing deposits	0	0
Short-term borrowings	0	0
Accrued interest payable	0	0
Carrying Value [Member]
Financial assets [Abstract]
Cash and cash equivalents	555,649	544,016
Securities available for sale	908,446	912,092
Held to maturity securities	91,278	143,426
Federal Reserve Bank and Federal Home Loan Bank stock	10,500	9,632
Net loans	2,787,247	2,636,806
Accrued interest receivable	11,700	11,752
Financial liabilities [Abstract]
Demand deposits	314,660	300,544
Interest bearing deposits	3,579,708	3,503,649
Short-term borrowings	185,226	159,846
Accrued interest payable	$ 438	$ 449

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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 Available-for-sale Securities which consist of all investments in certain debt and equity securities neither classified as trading or held-to-maturity securities. A debt security represents a creditor relationship with an enterprise. Debt securities include, among other items, US Treasury securities, US government securities, municipal securities, corporate bonds, convertible debt, commercial paper, and all securitized debt instruments. An equity security represents an ownership interest in an enterprise or the right to acquire or dispose of an ownership interest in an enterprise at fixed or determinable prices. Equity securities include, among other things, common stock, certain preferred stock, warrant rights, call options, and put options, but do not include convertible debt. An entity may opt to provide the reader with additional narrative text to better understand the nature of investments in debt and equity securities which are categorized as Available-for-sale.

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Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

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Carrying amount as of the balance sheet date of interest earned but not received. Also called accrued interest or accrued interest receivable.

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