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Net Carrying Value of Core Deposit Intangibles (Details) (USD $) | 12 Months Ended
--- | ---
Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012
Net Core Deposit Intangibles and Aggregate Amortization Expense |  |  |
Net carrying value | $ 10,900,000us-gaap_FiniteLivedIntangibleAssetsNet | $ 9,512,000us-gaap_FiniteLivedIntangibleAssetsNet |
Aggregate amortization expense | 2,811,000us-gaap_AmortizationOfIntangibleAssets | 2,401,000us-gaap_AmortizationOfIntangibleAssets | 2,110,000us-gaap_AmortizationOfIntangibleAssets
Core Deposits Intangibles |  |  |
Net Core Deposit Intangibles and Aggregate Amortization Expense |  |  |
Gross carrying value | 32,056,000us-gaap_FiniteLivedIntangibleAssetsGross / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_CoreDepositsMember | 27,857,000us-gaap_FiniteLivedIntangibleAssetsGross / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_CoreDepositsMember | 22,404,000us-gaap_FiniteLivedIntangibleAssetsGross / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_CoreDepositsMember
Accumulated amortization | (21,156,000)us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_CoreDepositsMember | (18,345,000)us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_CoreDepositsMember | (16,230,000)us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_CoreDepositsMember
Net carrying value | 10,900,000us-gaap_FiniteLivedIntangibleAssetsNet / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_CoreDepositsMember | 9,512,000us-gaap_FiniteLivedIntangibleAssetsNet / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_CoreDepositsMember | 6,174,000us-gaap_FiniteLivedIntangibleAssetsNet / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_CoreDepositsMember
Aggregate amortization expense | 2,811,000us-gaap_AmortizationOfIntangibleAssets / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_CoreDepositsMember | 2,401,000us-gaap_AmortizationOfIntangibleAssets / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_CoreDepositsMember | 2,110,000us-gaap_AmortizationOfIntangibleAssets / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_CoreDepositsMember
Estimated Amortization Expense |  |  |
For the year ending December 31, 2015 | 2,676,000us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_CoreDepositsMember |  |
For the year ending December 31, 2016 | 2,170,000us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_CoreDepositsMember |  |
For the year ending December 31, 2017 | 1,287,000us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_CoreDepositsMember |  |
For the year ending December 31, 2018 | 876,000us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_CoreDepositsMember |  |
For the year ending December 31, 2019 | 810,000us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_CoreDepositsMember |  |
Core Deposit Intangibles Acquired During the Year |  |  |
Core Deposit Intangibles Acquired | $ 4,199,000us-gaap_FinitelivedIntangibleAssetsAcquired1 / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_CoreDepositsMember | $ 5,739,000us-gaap_FinitelivedIntangibleAssetsAcquired1 / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_CoreDepositsMember |
Core Deposits Intangibles | Weighted Average |  |  |
Net Core Deposit Intangibles and Aggregate Amortization Expense |  |  |
Weighted-average amortization period (Period in years) | 9 years 7 months |  |

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- Definition Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275 + Details
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- Definition Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275 + Details
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- Definition Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275 + Details
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