XML 58 R68.htm IDEA: XBRL DOCUMENT v2.4.1.9
FAIR VALUE MEASUREMENTS (Details 4) (USD $)
3 Months Ended 12 Months Ended
Mar. 31, 2015
Dec. 31, 2014
Quantitative information about the significant unobservable inputs within Level 3    
Other real estate owned $ 1,444,000us-gaap_RealEstateAcquiredThroughForeclosure $ 2,049,000us-gaap_RealEstateAcquiredThroughForeclosure
Liabilities measured on non-recurring basis 0us-gaap_LiabilitiesFairValueDisclosureNonrecurring 0us-gaap_LiabilitiesFairValueDisclosureNonrecurring
Recurring    
Quantitative information about the significant unobservable inputs within Level 3    
Fair Value Instruments Transfers between Levels 0bhlb_FairValueInstrumentsTransfersBetweenLevels
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= us-gaap_FairValueMeasurementsRecurringMember
0bhlb_FairValueInstrumentsTransfersBetweenLevels
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
Non-recurring    
Quantitative information about the significant unobservable inputs within Level 3    
Fair Value Instruments Transfers between Levels 0bhlb_FairValueInstrumentsTransfersBetweenLevels
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsNonrecurringMember
0bhlb_FairValueInstrumentsTransfersBetweenLevels
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsNonrecurringMember
Non-recurring | Total Gains (Losses)    
Quantitative information about the significant unobservable inputs within Level 3    
Impaired loans 292,000bhlb_ImpairedLoansFairValueDisclosure
/ us-gaap_FairValueByMeasurementBasisAxis
= us-gaap_ChangeDuringPeriodFairValueDisclosureMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsNonrecurringMember
 
Other real estate owned (155,000)us-gaap_RealEstateAcquiredThroughForeclosure
/ us-gaap_FairValueByMeasurementBasisAxis
= us-gaap_ChangeDuringPeriodFairValueDisclosureMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsNonrecurringMember
 
Total 137,000us-gaap_AssetsFairValueDisclosure
/ us-gaap_FairValueByMeasurementBasisAxis
= us-gaap_ChangeDuringPeriodFairValueDisclosureMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsNonrecurringMember
 
Level 3 | Recurring    
Quantitative information about the significant unobservable inputs within Level 3    
Assets measured on recurring basis 16,573,000us-gaap_AssetsFairValueDisclosureRecurring
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
17,767,000us-gaap_AssetsFairValueDisclosureRecurring
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
Level 3 | Recurring | Trading Security | Discounted Cash Flow    
Quantitative information about the significant unobservable inputs within Level 3    
Assets measured on recurring basis 14,970,000us-gaap_AssetsFairValueDisclosureRecurring
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_TradingAccountAssetsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_ValuationTechniqueAxis
= bhlb_DiscountedCashFlowValuationTechniqueMember
14,909,000us-gaap_AssetsFairValueDisclosureRecurring
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_TradingAccountAssetsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_ValuationTechniqueAxis
= bhlb_DiscountedCashFlowValuationTechniqueMember
Discount Rate (as percent) 2.34%us-gaap_FairValueInputsDiscountRate
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_TradingAccountAssetsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_ValuationTechniqueAxis
= bhlb_DiscountedCashFlowValuationTechniqueMember
2.60%us-gaap_FairValueInputsDiscountRate
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_TradingAccountAssetsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_ValuationTechniqueAxis
= bhlb_DiscountedCashFlowValuationTechniqueMember
Level 3 | Recurring | Securities Available for Sale | Discounted Cash Flow    
Quantitative information about the significant unobservable inputs within Level 3    
Assets measured on recurring basis   2,326,000us-gaap_AssetsFairValueDisclosureRecurring
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_AvailableforsaleSecuritiesMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_ValuationTechniqueAxis
= bhlb_DiscountedCashFlowValuationTechniqueMember
Discount Rate (as percent)   13.74%us-gaap_FairValueInputsDiscountRate
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_AvailableforsaleSecuritiesMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_ValuationTechniqueAxis
= bhlb_DiscountedCashFlowValuationTechniqueMember
Credit Spread (as a percent)   11.06%us-gaap_FairValueInputsEntityCreditRisk
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_AvailableforsaleSecuritiesMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_ValuationTechniqueAxis
= bhlb_DiscountedCashFlowValuationTechniqueMember
Level 3 | Recurring | Securities Available for Sale | Pricing Model    
Quantitative information about the significant unobservable inputs within Level 3    
Assets measured on recurring basis 719,000us-gaap_AssetsFairValueDisclosureRecurring
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_AvailableforsaleSecuritiesMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_ValuationTechniqueAxis
= bhlb_PricingModelValuationTechniqueMember
 
Median Peer Price / Tangible Book Value Percentage Multiple (as a percent) 93.35%bhlb_FairValueInputsMedianPeerPrice
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_AvailableforsaleSecuritiesMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_ValuationTechniqueAxis
= bhlb_PricingModelValuationTechniqueMember
 
Level 3 | Recurring | Forward Commitments | Historical Trend    
Quantitative information about the significant unobservable inputs within Level 3    
Liabilities measured at fair value (93,000)us-gaap_LiabilitiesFairValueDisclosure
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_ForwardContractsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_ValuationTechniqueAxis
= bhlb_HistoricalTrendValuationTechniqueMember
(93,000)us-gaap_LiabilitiesFairValueDisclosure
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_ForwardContractsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_ValuationTechniqueAxis
= bhlb_HistoricalTrendValuationTechniqueMember
Closing Ratio (as percent) 89.54%bhlb_FairValueInputsClosingRatio
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_ForwardContractsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_ValuationTechniqueAxis
= bhlb_HistoricalTrendValuationTechniqueMember
91.07%bhlb_FairValueInputsClosingRatio
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_ForwardContractsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_ValuationTechniqueAxis
= bhlb_HistoricalTrendValuationTechniqueMember
Level 3 | Recurring | Forward Commitments | Pricing Model    
Quantitative information about the significant unobservable inputs within Level 3    
Origination Costs 2,500,000bhlb_FairValueInputsOriginationCosts
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_ForwardContractsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_ValuationTechniqueAxis
= bhlb_PricingModelValuationTechniqueMember
2,500,000bhlb_FairValueInputsOriginationCosts
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_ForwardContractsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_ValuationTechniqueAxis
= bhlb_PricingModelValuationTechniqueMember
Level 3 | Recurring | Interest rate lock commitments | Historical Trend    
Quantitative information about the significant unobservable inputs within Level 3    
Assets measured on recurring basis 977,000us-gaap_AssetsFairValueDisclosureRecurring
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_InterestRateLockCommitmentsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_ValuationTechniqueAxis
= bhlb_HistoricalTrendValuationTechniqueMember
625,000us-gaap_AssetsFairValueDisclosureRecurring
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_InterestRateLockCommitmentsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_ValuationTechniqueAxis
= bhlb_HistoricalTrendValuationTechniqueMember
Closing Ratio (as percent) 89.54%bhlb_FairValueInputsClosingRatio
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_InterestRateLockCommitmentsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_ValuationTechniqueAxis
= bhlb_HistoricalTrendValuationTechniqueMember
91.07%bhlb_FairValueInputsClosingRatio
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_InterestRateLockCommitmentsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_ValuationTechniqueAxis
= bhlb_HistoricalTrendValuationTechniqueMember
Level 3 | Recurring | Interest rate lock commitments | Pricing Model    
Quantitative information about the significant unobservable inputs within Level 3    
Origination Costs 2,500,000bhlb_FairValueInputsOriginationCosts
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_InterestRateLockCommitmentsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_ValuationTechniqueAxis
= bhlb_PricingModelValuationTechniqueMember
2,500,000bhlb_FairValueInputsOriginationCosts
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= us-gaap_InterestRateLockCommitmentsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_ValuationTechniqueAxis
= bhlb_PricingModelValuationTechniqueMember
Level 3 | Non-recurring    
Quantitative information about the significant unobservable inputs within Level 3    
Impaired loans 6,111,000bhlb_ImpairedLoansFairValueDisclosure
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= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsNonrecurringMember
5,820,000bhlb_ImpairedLoansFairValueDisclosure
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= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsNonrecurringMember
Capitalized mortgage servicing rights 3,871,000us-gaap_ServicingAssetAtFairValueAmount
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3,757,000us-gaap_ServicingAssetAtFairValueAmount
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsNonrecurringMember
Other real estate owned 1,444,000us-gaap_RealEstateAcquiredThroughForeclosure
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/ us-gaap_FairValueByMeasurementFrequencyAxis
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2,049,000us-gaap_RealEstateAcquiredThroughForeclosure
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= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsNonrecurringMember
Total 11,426,000us-gaap_AssetsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
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11,626,000us-gaap_AssetsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsNonrecurringMember
Level 3 | Non-recurring | Minimum | Impaired loans    
Quantitative information about the significant unobservable inputs within Level 3    
Loss severity (as percent)   0.31%us-gaap_FairValueInputsLossSeverity
/ us-gaap_FairValueByAssetClassAxis
= bhlb_ImpairedLoansMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsNonrecurringMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
Level 3 | Non-recurring | Minimum | Impaired loans | Fair value of collateral    
Quantitative information about the significant unobservable inputs within Level 3    
Loss severity (as percent) 3.78%us-gaap_FairValueInputsLossSeverity
/ us-gaap_FairValueByAssetClassAxis
= bhlb_ImpairedLoansMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
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/ us-gaap_RangeAxis
= us-gaap_MinimumMember
/ us-gaap_ValuationTechniqueAxis
= bhlb_FairValueOfCollateralValuationTechniqueMember
5.00%us-gaap_FairValueInputsLossSeverity
/ us-gaap_FairValueByAssetClassAxis
= bhlb_ImpairedLoansMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
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/ us-gaap_RangeAxis
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/ us-gaap_ValuationTechniqueAxis
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Appraised value 139,500bhlb_FairValueInputsAppraisedValue
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= bhlb_ImpairedLoansMember
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/ us-gaap_RangeAxis
= us-gaap_MinimumMember
/ us-gaap_ValuationTechniqueAxis
= bhlb_FairValueOfCollateralValuationTechniqueMember
 
Level 3 | Non-recurring | Minimum | Capitalized mortgage servicing rights    
Quantitative information about the significant unobservable inputs within Level 3    
Constant prepayment rate (CPR) (as percent)   7.83%us-gaap_FairValueInputsPrepaymentRate
/ us-gaap_FairValueByAssetClassAxis
= bhlb_CapitalizedMortgageServicingRightsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
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/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsNonrecurringMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
Level 3 | Non-recurring | Minimum | Capitalized mortgage servicing rights | Discounted Cash Flow    
Quantitative information about the significant unobservable inputs within Level 3    
Discount Rate (as percent) 10.00%us-gaap_FairValueInputsDiscountRate
/ us-gaap_FairValueByAssetClassAxis
= bhlb_CapitalizedMortgageServicingRightsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
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/ us-gaap_FairValueByMeasurementFrequencyAxis
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/ us-gaap_RangeAxis
= us-gaap_MinimumMember
/ us-gaap_ValuationTechniqueAxis
= bhlb_DiscountedCashFlowValuationTechniqueMember
 
Constant prepayment rate (CPR) (as percent) 8.20%us-gaap_FairValueInputsPrepaymentRate
/ us-gaap_FairValueByAssetClassAxis
= bhlb_CapitalizedMortgageServicingRightsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsNonrecurringMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
/ us-gaap_ValuationTechniqueAxis
= bhlb_DiscountedCashFlowValuationTechniqueMember
10.00%us-gaap_FairValueInputsPrepaymentRate
/ us-gaap_FairValueByAssetClassAxis
= bhlb_CapitalizedMortgageServicingRightsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
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/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsNonrecurringMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
/ us-gaap_ValuationTechniqueAxis
= bhlb_DiscountedCashFlowValuationTechniqueMember
Level 3 | Non-recurring | Minimum | Other real estate owned    
Quantitative information about the significant unobservable inputs within Level 3    
Appraised value   57,000bhlb_FairValueInputsAppraisedValue
/ us-gaap_FairValueByAssetClassAxis
= bhlb_OtherRealEstateOwnedMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsNonrecurringMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
Level 3 | Non-recurring | Minimum | Other real estate owned | Fair value of collateral    
Quantitative information about the significant unobservable inputs within Level 3    
Appraised value 57,000bhlb_FairValueInputsAppraisedValue
/ us-gaap_FairValueByAssetClassAxis
= bhlb_OtherRealEstateOwnedMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
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/ us-gaap_RangeAxis
= us-gaap_MinimumMember
/ us-gaap_ValuationTechniqueAxis
= bhlb_FairValueOfCollateralValuationTechniqueMember
 
Level 3 | Non-recurring | Maximum | Impaired loans    
Quantitative information about the significant unobservable inputs within Level 3    
Loss severity (as percent)   38.70%us-gaap_FairValueInputsLossSeverity
/ us-gaap_FairValueByAssetClassAxis
= bhlb_ImpairedLoansMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsNonrecurringMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
Level 3 | Non-recurring | Maximum | Impaired loans | Fair value of collateral    
Quantitative information about the significant unobservable inputs within Level 3    
Loss severity (as percent) 53.08%us-gaap_FairValueInputsLossSeverity
/ us-gaap_FairValueByAssetClassAxis
= bhlb_ImpairedLoansMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsNonrecurringMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
/ us-gaap_ValuationTechniqueAxis
= bhlb_FairValueOfCollateralValuationTechniqueMember
1600.00%us-gaap_FairValueInputsLossSeverity
/ us-gaap_FairValueByAssetClassAxis
= bhlb_ImpairedLoansMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsNonrecurringMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
/ us-gaap_ValuationTechniqueAxis
= bhlb_FairValueOfCollateralValuationTechniqueMember
Appraised value 1,600,000bhlb_FairValueInputsAppraisedValue
/ us-gaap_FairValueByAssetClassAxis
= bhlb_ImpairedLoansMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsNonrecurringMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
/ us-gaap_ValuationTechniqueAxis
= bhlb_FairValueOfCollateralValuationTechniqueMember
 
Level 3 | Non-recurring | Maximum | Capitalized mortgage servicing rights    
Quantitative information about the significant unobservable inputs within Level 3    
Constant prepayment rate (CPR) (as percent)   19.00%us-gaap_FairValueInputsPrepaymentRate
/ us-gaap_FairValueByAssetClassAxis
= bhlb_CapitalizedMortgageServicingRightsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsNonrecurringMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
Level 3 | Non-recurring | Maximum | Capitalized mortgage servicing rights | Discounted Cash Flow    
Quantitative information about the significant unobservable inputs within Level 3    
Discount Rate (as percent) 13.00%us-gaap_FairValueInputsDiscountRate
/ us-gaap_FairValueByAssetClassAxis
= bhlb_CapitalizedMortgageServicingRightsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
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/ us-gaap_RangeAxis
= us-gaap_MaximumMember
/ us-gaap_ValuationTechniqueAxis
= bhlb_DiscountedCashFlowValuationTechniqueMember
 
Constant prepayment rate (CPR) (as percent) 19.85%us-gaap_FairValueInputsPrepaymentRate
/ us-gaap_FairValueByAssetClassAxis
= bhlb_CapitalizedMortgageServicingRightsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
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/ us-gaap_RangeAxis
= us-gaap_MaximumMember
/ us-gaap_ValuationTechniqueAxis
= bhlb_DiscountedCashFlowValuationTechniqueMember
13.00%us-gaap_FairValueInputsPrepaymentRate
/ us-gaap_FairValueByAssetClassAxis
= bhlb_CapitalizedMortgageServicingRightsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsNonrecurringMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
/ us-gaap_ValuationTechniqueAxis
= bhlb_DiscountedCashFlowValuationTechniqueMember
Level 3 | Non-recurring | Maximum | Other real estate owned    
Quantitative information about the significant unobservable inputs within Level 3    
Appraised value   700,000bhlb_FairValueInputsAppraisedValue
/ us-gaap_FairValueByAssetClassAxis
= bhlb_OtherRealEstateOwnedMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsNonrecurringMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
Level 3 | Non-recurring | Maximum | Other real estate owned | Fair value of collateral    
Quantitative information about the significant unobservable inputs within Level 3    
Appraised value 700,000bhlb_FairValueInputsAppraisedValue
/ us-gaap_FairValueByAssetClassAxis
= bhlb_OtherRealEstateOwnedMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsNonrecurringMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
/ us-gaap_ValuationTechniqueAxis
= bhlb_FairValueOfCollateralValuationTechniqueMember
 
Level 3 | Non-recurring | Weighted Average | Impaired loans    
Quantitative information about the significant unobservable inputs within Level 3    
Loss severity (as percent)   12.65%us-gaap_FairValueInputsLossSeverity
/ us-gaap_FairValueByAssetClassAxis
= bhlb_ImpairedLoansMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsNonrecurringMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
Level 3 | Non-recurring | Weighted Average | Impaired loans | Fair value of collateral    
Quantitative information about the significant unobservable inputs within Level 3    
Loss severity (as percent) 23.50%us-gaap_FairValueInputsLossSeverity
/ us-gaap_FairValueByAssetClassAxis
= bhlb_ImpairedLoansMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsNonrecurringMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
/ us-gaap_ValuationTechniqueAxis
= bhlb_FairValueOfCollateralValuationTechniqueMember
912.70%us-gaap_FairValueInputsLossSeverity
/ us-gaap_FairValueByAssetClassAxis
= bhlb_ImpairedLoansMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsNonrecurringMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
/ us-gaap_ValuationTechniqueAxis
= bhlb_FairValueOfCollateralValuationTechniqueMember
Appraised value 981,700bhlb_FairValueInputsAppraisedValue
/ us-gaap_FairValueByAssetClassAxis
= bhlb_ImpairedLoansMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsNonrecurringMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
/ us-gaap_ValuationTechniqueAxis
= bhlb_FairValueOfCollateralValuationTechniqueMember
 
Level 3 | Non-recurring | Weighted Average | Capitalized mortgage servicing rights    
Quantitative information about the significant unobservable inputs within Level 3    
Constant prepayment rate (CPR) (as percent)   9.92%us-gaap_FairValueInputsPrepaymentRate
/ us-gaap_FairValueByAssetClassAxis
= bhlb_CapitalizedMortgageServicingRightsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsNonrecurringMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
Level 3 | Non-recurring | Weighted Average | Capitalized mortgage servicing rights | Discounted Cash Flow    
Quantitative information about the significant unobservable inputs within Level 3    
Discount Rate (as percent) 10.42%us-gaap_FairValueInputsDiscountRate
/ us-gaap_FairValueByAssetClassAxis
= bhlb_CapitalizedMortgageServicingRightsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsNonrecurringMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
/ us-gaap_ValuationTechniqueAxis
= bhlb_DiscountedCashFlowValuationTechniqueMember
 
Constant prepayment rate (CPR) (as percent) 11.05%us-gaap_FairValueInputsPrepaymentRate
/ us-gaap_FairValueByAssetClassAxis
= bhlb_CapitalizedMortgageServicingRightsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsNonrecurringMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
/ us-gaap_ValuationTechniqueAxis
= bhlb_DiscountedCashFlowValuationTechniqueMember
10.43%us-gaap_FairValueInputsPrepaymentRate
/ us-gaap_FairValueByAssetClassAxis
= bhlb_CapitalizedMortgageServicingRightsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsNonrecurringMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
/ us-gaap_ValuationTechniqueAxis
= bhlb_DiscountedCashFlowValuationTechniqueMember
Level 3 | Non-recurring | Weighted Average | Other real estate owned    
Quantitative information about the significant unobservable inputs within Level 3    
Appraised value   462,600bhlb_FairValueInputsAppraisedValue
/ us-gaap_FairValueByAssetClassAxis
= bhlb_OtherRealEstateOwnedMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsNonrecurringMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
Level 3 | Non-recurring | Weighted Average | Other real estate owned | Fair value of collateral    
Quantitative information about the significant unobservable inputs within Level 3    
Appraised value $ 470,700bhlb_FairValueInputsAppraisedValue
/ us-gaap_FairValueByAssetClassAxis
= bhlb_OtherRealEstateOwnedMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsNonrecurringMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
/ us-gaap_ValuationTechniqueAxis
= bhlb_FairValueOfCollateralValuationTechniqueMember