Investment Securities (Details Textual) (USD $)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Jan. 01, 2014
Investment Securities
Investment securities pledged as collateral	$ 1,673,263,000	$ 1,635,316,000
Other-than-temporary impairment on investment securities	0us-gaap_ImpairmentOfInvestments	0us-gaap_ImpairmentOfInvestments
State and local governments
Investment Securities
Available-for-sale Securities, Transferred to Held-to-Maturity Securities, Fair Value			484,583,000
Available-for-sale Securities, Transferred to Held-to-Maturity Securities, Unrealized Gain (Loss)			$ 4,624,000

For any transfer of securities categorized as available-for-sale, this item represents the estimated fair value of the transferred security to held-to-maturity securities.

No definition available.

+ Details

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- Definition

This item represents the unrealized gain (loss) recognized in other comprehensive income (a separate component of shareholders' equity) prior to the available-for-sale securities being transferred to the held-to-maturity category.

+ References

No definition available.

+ Details

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- Definition

The amount by which the fair value of an investment is less than the amortized cost basis or carrying amount of that investment at the balance sheet date and the decline in fair value is deemed to be other than temporary, before considering whether or not such amount is recognized in earnings or other comprehensive income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 35

-Paragraph 34

-URI http://asc.fasb.org/extlink&oid=27723805&loc=d3e25351-111560

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- Definition

Fair value of financial instrument held by the entity for its own account (proprietary securities) for trading or investment purposes that are carried at fair value and pledged to counterparties as collateral for financing transactions.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 860

-SubTopic 30

-Section 50

-Paragraph 1A

-Subparagraph (b)(1)(i)

-URI http://asc.fasb.org/extlink&oid=34720971&loc=SL6224234-111729

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 860

-SubTopic 30

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6467456&loc=d3e113888-111728

+ Details

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- Details

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