XML 122 R63.htm IDEA: XBRL DOCUMENT v2.4.1.9
SECURITIES (Details) (USD $)
In Thousands, unless otherwise specified
Dec. 31, 2014
Dec. 31, 2013
Securities available for sale:    
Amortized Cost $ 1,075,824us-gaap_AvailableForSaleSecuritiesAmortizedCost $ 769,342us-gaap_AvailableForSaleSecuritiesAmortizedCost
Gross Unrealized Gains 23,244bhlb_AvailableForSaleSecuritiesGrossUnrealizedGainAccumulatedInInvestments 8,005bhlb_AvailableForSaleSecuritiesGrossUnrealizedGainAccumulatedInInvestments
Gross Unrealized Losses (7,250)bhlb_AvailableForSaleSecuritiesGrossUnrealizedLossAccumulatedInInvestments (17,299)bhlb_AvailableForSaleSecuritiesGrossUnrealizedLossAccumulatedInInvestments
Fair Value 1,091,818us-gaap_AvailableForSaleSecurities 760,048us-gaap_AvailableForSaleSecurities
Securities held to maturity    
Amortized Cost 43,347us-gaap_HeldToMaturitySecurities 44,921us-gaap_HeldToMaturitySecurities
Gross Unrealized Gains 1,684bhlb_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain 1,257bhlb_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain
Gross Unrealized Losses (34)bhlb_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss (414)bhlb_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss
Fair Value 44,997us-gaap_HeldToMaturitySecuritiesFairValue 45,764us-gaap_HeldToMaturitySecuritiesFairValue
Securities    
Total Amortized Cost 1,119,171bhlb_HeldToMaturityAndAvailableForSaleSecuritiesAmortizedCost 814,263bhlb_HeldToMaturityAndAvailableForSaleSecuritiesAmortizedCost
Total Gross Unrealized Gains 24,928bhlb_HeldToMaturityAndAvailableForSaleSecuritiesGrossUnrealizedGain 9,262bhlb_HeldToMaturityAndAvailableForSaleSecuritiesGrossUnrealizedGain
Total Gross Unrealized Losses (7,284)bhlb_HeldToMaturityAndAvailableForSaleSecuritiesGrossUnrealizedLosses (17,713)bhlb_HeldToMaturityAndAvailableForSaleSecuritiesGrossUnrealizedLosses
Total Fair Value 1,136,815us-gaap_AvailableForSaleSecuritiesAndHeldToMaturitySecurities 805,812us-gaap_AvailableForSaleSecuritiesAndHeldToMaturitySecurities
Debt securities    
Securities available for sale:    
Amortized Cost 1,026,831us-gaap_AvailableForSaleSecuritiesAmortizedCost
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= us-gaap_DebtSecuritiesMember
749,300us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
Gross Unrealized Gains 15,922bhlb_AvailableForSaleSecuritiesGrossUnrealizedGainAccumulatedInInvestments
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
5,739bhlb_AvailableForSaleSecuritiesGrossUnrealizedGainAccumulatedInInvestments
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
Gross Unrealized Losses (5,877)bhlb_AvailableForSaleSecuritiesGrossUnrealizedLossAccumulatedInInvestments
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
(16,964)bhlb_AvailableForSaleSecuritiesGrossUnrealizedLossAccumulatedInInvestments
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
Fair Value 1,036,876us-gaap_AvailableForSaleSecurities
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
738,075us-gaap_AvailableForSaleSecurities
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
Debt securities | Municipal bonds and obligations    
Securities available for sale:    
Amortized Cost 127,014us-gaap_AvailableForSaleSecuritiesAmortizedCost
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= us-gaap_USStatesAndPoliticalSubdivisionsMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
77,852us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_InvestmentTypeAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
Gross Unrealized Gains 6,859bhlb_AvailableForSaleSecuritiesGrossUnrealizedGainAccumulatedInInvestments
/ us-gaap_InvestmentTypeAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
1,789bhlb_AvailableForSaleSecuritiesGrossUnrealizedGainAccumulatedInInvestments
/ us-gaap_InvestmentTypeAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
Gross Unrealized Losses (174)bhlb_AvailableForSaleSecuritiesGrossUnrealizedLossAccumulatedInInvestments
/ us-gaap_InvestmentTypeAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
(1,970)bhlb_AvailableForSaleSecuritiesGrossUnrealizedLossAccumulatedInInvestments
/ us-gaap_InvestmentTypeAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
Fair Value 133,699us-gaap_AvailableForSaleSecurities
/ us-gaap_InvestmentTypeAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
77,671us-gaap_AvailableForSaleSecurities
/ us-gaap_InvestmentTypeAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
Securities held to maturity    
Amortized Cost 4,997us-gaap_HeldToMaturitySecurities
/ us-gaap_InvestmentTypeAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
4,244us-gaap_HeldToMaturitySecurities
/ us-gaap_InvestmentTypeAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
Fair Value 4,997us-gaap_HeldToMaturitySecuritiesFairValue
/ us-gaap_InvestmentTypeAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
4,244us-gaap_HeldToMaturitySecuritiesFairValue
/ us-gaap_InvestmentTypeAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
Debt securities | Government guaranteed residential mortgage-backed securities    
Securities available for sale:    
Amortized Cost 68,972us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_InvestmentTypeAxis
= bhlb_ResidentialMortgageBackedSecuritiesGuaranteedByUSGovernmentMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
78,885us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_InvestmentTypeAxis
= bhlb_ResidentialMortgageBackedSecuritiesGuaranteedByUSGovernmentMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
Gross Unrealized Gains 702bhlb_AvailableForSaleSecuritiesGrossUnrealizedGainAccumulatedInInvestments
/ us-gaap_InvestmentTypeAxis
= bhlb_ResidentialMortgageBackedSecuritiesGuaranteedByUSGovernmentMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
544bhlb_AvailableForSaleSecuritiesGrossUnrealizedGainAccumulatedInInvestments
/ us-gaap_InvestmentTypeAxis
= bhlb_ResidentialMortgageBackedSecuritiesGuaranteedByUSGovernmentMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
Gross Unrealized Losses (206)bhlb_AvailableForSaleSecuritiesGrossUnrealizedLossAccumulatedInInvestments
/ us-gaap_InvestmentTypeAxis
= bhlb_ResidentialMortgageBackedSecuritiesGuaranteedByUSGovernmentMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
(658)bhlb_AvailableForSaleSecuritiesGrossUnrealizedLossAccumulatedInInvestments
/ us-gaap_InvestmentTypeAxis
= bhlb_ResidentialMortgageBackedSecuritiesGuaranteedByUSGovernmentMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
Fair Value 69,468us-gaap_AvailableForSaleSecurities
/ us-gaap_InvestmentTypeAxis
= bhlb_ResidentialMortgageBackedSecuritiesGuaranteedByUSGovernmentMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
78,771us-gaap_AvailableForSaleSecurities
/ us-gaap_InvestmentTypeAxis
= bhlb_ResidentialMortgageBackedSecuritiesGuaranteedByUSGovernmentMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
Debt securities | Government-sponsored residential mortgage-backed securities    
Securities available for sale:    
Amortized Cost 755,893us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_InvestmentTypeAxis
= us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
531,441us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_InvestmentTypeAxis
= us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
Gross Unrealized Gains 7,421bhlb_AvailableForSaleSecuritiesGrossUnrealizedGainAccumulatedInInvestments
/ us-gaap_InvestmentTypeAxis
= us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
2,000bhlb_AvailableForSaleSecuritiesGrossUnrealizedGainAccumulatedInInvestments
/ us-gaap_InvestmentTypeAxis
= us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
Gross Unrealized Losses (3,130)bhlb_AvailableForSaleSecuritiesGrossUnrealizedLossAccumulatedInInvestments
/ us-gaap_InvestmentTypeAxis
= us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
(10,783)bhlb_AvailableForSaleSecuritiesGrossUnrealizedLossAccumulatedInInvestments
/ us-gaap_InvestmentTypeAxis
= us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember
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= us-gaap_DebtSecuritiesMember
Fair Value 760,184us-gaap_AvailableForSaleSecurities
/ us-gaap_InvestmentTypeAxis
= us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
522,658us-gaap_AvailableForSaleSecurities
/ us-gaap_InvestmentTypeAxis
= us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
Securities held to maturity    
Amortized Cost 70us-gaap_HeldToMaturitySecurities
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= us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
73us-gaap_HeldToMaturitySecurities
/ us-gaap_InvestmentTypeAxis
= us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
Gross Unrealized Gains 4bhlb_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain
/ us-gaap_InvestmentTypeAxis
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/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
2bhlb_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain
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/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
Fair Value 74us-gaap_HeldToMaturitySecuritiesFairValue
/ us-gaap_InvestmentTypeAxis
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/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
75us-gaap_HeldToMaturitySecuritiesFairValue
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= us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
Debt securities | Corporate bonds    
Securities available for sale:    
Amortized Cost 55,134us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateBondSecuritiesMember
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40,945us-gaap_AvailableForSaleSecuritiesAmortizedCost
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= us-gaap_CorporateBondSecuritiesMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
Gross Unrealized Gains 120bhlb_AvailableForSaleSecuritiesGrossUnrealizedGainAccumulatedInInvestments
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateBondSecuritiesMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
157bhlb_AvailableForSaleSecuritiesGrossUnrealizedGainAccumulatedInInvestments
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateBondSecuritiesMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
Gross Unrealized Losses (1,103)bhlb_AvailableForSaleSecuritiesGrossUnrealizedLossAccumulatedInInvestments
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateBondSecuritiesMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
(1,822)bhlb_AvailableForSaleSecuritiesGrossUnrealizedLossAccumulatedInInvestments
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateBondSecuritiesMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
Fair Value 54,151us-gaap_AvailableForSaleSecurities
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateBondSecuritiesMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
39,280us-gaap_AvailableForSaleSecurities
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateBondSecuritiesMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
Debt securities | Trust preferred securities    
Securities available for sale:    
Amortized Cost 16,607us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_InvestmentTypeAxis
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= us-gaap_DebtSecuritiesMember
16,927us-gaap_AvailableForSaleSecuritiesAmortizedCost
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= us-gaap_TrustPreferredSecuritiesSubjectToMandatoryRedemptionMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
Gross Unrealized Gains 820bhlb_AvailableForSaleSecuritiesGrossUnrealizedGainAccumulatedInInvestments
/ us-gaap_InvestmentTypeAxis
= us-gaap_TrustPreferredSecuritiesSubjectToMandatoryRedemptionMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
1,249bhlb_AvailableForSaleSecuritiesGrossUnrealizedGainAccumulatedInInvestments
/ us-gaap_InvestmentTypeAxis
= us-gaap_TrustPreferredSecuritiesSubjectToMandatoryRedemptionMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
Gross Unrealized Losses (1,212)bhlb_AvailableForSaleSecuritiesGrossUnrealizedLossAccumulatedInInvestments
/ us-gaap_InvestmentTypeAxis
= us-gaap_TrustPreferredSecuritiesSubjectToMandatoryRedemptionMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
(1,565)bhlb_AvailableForSaleSecuritiesGrossUnrealizedLossAccumulatedInInvestments
/ us-gaap_InvestmentTypeAxis
= us-gaap_TrustPreferredSecuritiesSubjectToMandatoryRedemptionMember
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= us-gaap_DebtSecuritiesMember
Fair Value 16,215us-gaap_AvailableForSaleSecurities
/ us-gaap_InvestmentTypeAxis
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/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
16,611us-gaap_AvailableForSaleSecurities
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= us-gaap_TrustPreferredSecuritiesSubjectToMandatoryRedemptionMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
Debt securities | Tax advantaged economic development bonds    
Securities held to maturity    
Amortized Cost 37,948us-gaap_HeldToMaturitySecurities
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= bhlb_TaxAdvantagedEconomicDevelopmentBondsMember
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40,260us-gaap_HeldToMaturitySecurities
/ us-gaap_InvestmentTypeAxis
= bhlb_TaxAdvantagedEconomicDevelopmentBondsMember
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= us-gaap_DebtSecuritiesMember
Gross Unrealized Gains 1,680bhlb_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain
/ us-gaap_InvestmentTypeAxis
= bhlb_TaxAdvantagedEconomicDevelopmentBondsMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
1,255bhlb_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain
/ us-gaap_InvestmentTypeAxis
= bhlb_TaxAdvantagedEconomicDevelopmentBondsMember
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= us-gaap_DebtSecuritiesMember
Gross Unrealized Losses (34)bhlb_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss
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= bhlb_TaxAdvantagedEconomicDevelopmentBondsMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
(414)bhlb_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss
/ us-gaap_InvestmentTypeAxis
= bhlb_TaxAdvantagedEconomicDevelopmentBondsMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
Fair Value 39,594us-gaap_HeldToMaturitySecuritiesFairValue
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= bhlb_TaxAdvantagedEconomicDevelopmentBondsMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
41,101us-gaap_HeldToMaturitySecuritiesFairValue
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= bhlb_TaxAdvantagedEconomicDevelopmentBondsMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
Debt securities | Other bonds and obligations    
Securities available for sale:    
Amortized Cost 3,211us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_InvestmentTypeAxis
= us-gaap_OtherDebtSecuritiesMember
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= us-gaap_DebtSecuritiesMember
3,250us-gaap_AvailableForSaleSecuritiesAmortizedCost
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= us-gaap_OtherDebtSecuritiesMember
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= us-gaap_DebtSecuritiesMember
Gross Unrealized Losses (52)bhlb_AvailableForSaleSecuritiesGrossUnrealizedLossAccumulatedInInvestments
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= us-gaap_OtherDebtSecuritiesMember
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= us-gaap_DebtSecuritiesMember
(166)bhlb_AvailableForSaleSecuritiesGrossUnrealizedLossAccumulatedInInvestments
/ us-gaap_InvestmentTypeAxis
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= us-gaap_DebtSecuritiesMember
Fair Value 3,159us-gaap_AvailableForSaleSecurities
/ us-gaap_InvestmentTypeAxis
= us-gaap_OtherDebtSecuritiesMember
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= us-gaap_DebtSecuritiesMember
3,084us-gaap_AvailableForSaleSecurities
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= us-gaap_OtherDebtSecuritiesMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
Securities held to maturity    
Amortized Cost 332us-gaap_HeldToMaturitySecurities
/ us-gaap_InvestmentTypeAxis
= us-gaap_OtherDebtSecuritiesMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
344us-gaap_HeldToMaturitySecurities
/ us-gaap_InvestmentTypeAxis
= us-gaap_OtherDebtSecuritiesMember
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= us-gaap_DebtSecuritiesMember
Fair Value 332us-gaap_HeldToMaturitySecuritiesFairValue
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= us-gaap_DebtSecuritiesMember
344us-gaap_HeldToMaturitySecuritiesFairValue
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= us-gaap_OtherDebtSecuritiesMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_DebtSecuritiesMember
Marketable equity securities    
Securities available for sale:    
Amortized Cost 48,993us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_EquitySecuritiesMember
20,042us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_EquitySecuritiesMember
Gross Unrealized Gains 7,322bhlb_AvailableForSaleSecuritiesGrossUnrealizedGainAccumulatedInInvestments
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_EquitySecuritiesMember
2,266bhlb_AvailableForSaleSecuritiesGrossUnrealizedGainAccumulatedInInvestments
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_EquitySecuritiesMember
Gross Unrealized Losses (1,373)bhlb_AvailableForSaleSecuritiesGrossUnrealizedLossAccumulatedInInvestments
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_EquitySecuritiesMember
(335)bhlb_AvailableForSaleSecuritiesGrossUnrealizedLossAccumulatedInInvestments
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_EquitySecuritiesMember
Fair Value $ 54,942us-gaap_AvailableForSaleSecurities
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_EquitySecuritiesMember
$ 21,973us-gaap_AvailableForSaleSecurities
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_EquitySecuritiesMember