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Investment Securities (Unrealized Losses And Fair Value) (Details) (USD $)
In Thousands, unless otherwise specified
Dec. 31, 2014
Dec. 31, 2013
Securities [Line Items]    
Held-to-maturity Securities, Fair Value, Total $ 22,097us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionFairValue $ 31,672us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionFairValue
Held-to-maturity Securities, Unrealized Losses (576)dnbf_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionAggregateLoss2 (2,514)dnbf_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionAggregateLoss2
Held-to-maturity Securities, Fair Value Impaired Less Than 12 Months 5,181us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue 19,964us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
Held-to-maturity Securities, Unrealized Loss Less Than 12 Months (36)dnbf_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateAccumulatedLoss (816)dnbf_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateAccumulatedLoss
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value 16,916us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue 11,708us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses (540)dnbf_HeldToMaturitySecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateAccumulatedLoss (1,698)dnbf_HeldToMaturitySecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateAccumulatedLoss
Available-for-sale Securities, Fair Value, Total 112,713us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue 102,235us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue
Available-for-sale Securities, Unrealized Loss, Total (955)dnbf_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAggregateLossesAccumulatedInAoci (2,673)dnbf_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAggregateLossesAccumulatedInAoci
Available-for-sale Securities, Fair Value Impaired Less Than 12 Months 79,778us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue 94,790us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
Available-for-sale Securities, Unrealized Loss Less Than 12 Months (180)dnbf_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLossesAccumulatedInAoci (2,469)dnbf_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLossesAccumulatedInAoci
Available-for-sale Securities, Fair Value Impaired More Than 12 Months 32,935us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue 7,445us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
Available-for-sale Securities, Unrealized Loss More Than 12 Months (775)dnbf_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLossesAccumulatedInAoci (204)dnbf_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLossesAccumulatedInAoci
US Government Agency Obligations [Member]    
Securities [Line Items]    
Available-for-sale Securities, Fair Value, Total 56,342us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember
24,931us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember
Available-for-sale Securities, Unrealized Loss, Total (197)dnbf_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAggregateLossesAccumulatedInAoci
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember
(583)dnbf_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAggregateLossesAccumulatedInAoci
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember
Available-for-sale Securities, Fair Value Impaired Less Than 12 Months 49,222us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember
24,931us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember
Available-for-sale Securities, Unrealized Loss Less Than 12 Months (97)dnbf_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLossesAccumulatedInAoci
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember
(583)dnbf_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLossesAccumulatedInAoci
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember
Available-for-sale Securities, Fair Value Impaired More Than 12 Months 7,120us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember
 
Available-for-sale Securities, Unrealized Loss More Than 12 Months (100)dnbf_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLossesAccumulatedInAoci
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember
 
Government Sponsored Entities (GSE) Mortgage-Backed Securities [Member]    
Securities [Line Items]    
Available-for-sale Securities, Fair Value, Total 22,157us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember
38,255us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember
Available-for-sale Securities, Unrealized Loss, Total (135)dnbf_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAggregateLossesAccumulatedInAoci
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember
(698)dnbf_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAggregateLossesAccumulatedInAoci
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember
Available-for-sale Securities, Fair Value Impaired Less Than 12 Months 14,996us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember
38,255us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember
Available-for-sale Securities, Unrealized Loss Less Than 12 Months (38)dnbf_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLossesAccumulatedInAoci
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember
(698)dnbf_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLossesAccumulatedInAoci
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember
Available-for-sale Securities, Fair Value Impaired More Than 12 Months 7,161us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember
 
Available-for-sale Securities, Unrealized Loss More Than 12 Months (97)dnbf_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLossesAccumulatedInAoci
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember
 
Collateralized Mortgage Obligations GSE [Member]    
Securities [Line Items]    
Available-for-sale Securities, Fair Value, Total 18,133us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CollateralizedDebtObligationsMember
21,416us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CollateralizedDebtObligationsMember
Available-for-sale Securities, Unrealized Loss, Total (496)dnbf_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAggregateLossesAccumulatedInAoci
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CollateralizedDebtObligationsMember
(968)dnbf_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAggregateLossesAccumulatedInAoci
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CollateralizedDebtObligationsMember
Available-for-sale Securities, Fair Value Impaired Less Than 12 Months 3,669us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CollateralizedDebtObligationsMember
20,336us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CollateralizedDebtObligationsMember
Available-for-sale Securities, Unrealized Loss Less Than 12 Months (5)dnbf_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLossesAccumulatedInAoci
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CollateralizedDebtObligationsMember
(959)dnbf_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLossesAccumulatedInAoci
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CollateralizedDebtObligationsMember
Available-for-sale Securities, Fair Value Impaired More Than 12 Months 14,464us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CollateralizedDebtObligationsMember
1,080us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CollateralizedDebtObligationsMember
Available-for-sale Securities, Unrealized Loss More Than 12 Months (491)dnbf_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLossesAccumulatedInAoci
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CollateralizedDebtObligationsMember
(9)dnbf_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLossesAccumulatedInAoci
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CollateralizedDebtObligationsMember
Corporate Bonds [Member]    
Securities [Line Items]    
Available-for-sale Securities, Fair Value, Total 13,102us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CorporateDebtSecuritiesMember
16,549us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CorporateDebtSecuritiesMember
Available-for-sale Securities, Unrealized Loss, Total (106)dnbf_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAggregateLossesAccumulatedInAoci
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CorporateDebtSecuritiesMember
(394)dnbf_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAggregateLossesAccumulatedInAoci
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CorporateDebtSecuritiesMember
Available-for-sale Securities, Fair Value Impaired Less Than 12 Months 9,531us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CorporateDebtSecuritiesMember
10,968us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CorporateDebtSecuritiesMember
Available-for-sale Securities, Unrealized Loss Less Than 12 Months (31)dnbf_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLossesAccumulatedInAoci
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CorporateDebtSecuritiesMember
(223)dnbf_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLossesAccumulatedInAoci
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CorporateDebtSecuritiesMember
Available-for-sale Securities, Fair Value Impaired More Than 12 Months 3,571us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CorporateDebtSecuritiesMember
5,581us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CorporateDebtSecuritiesMember
Available-for-sale Securities, Unrealized Loss More Than 12 Months (75)dnbf_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLossesAccumulatedInAoci
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CorporateDebtSecuritiesMember
(171)dnbf_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLossesAccumulatedInAoci
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CorporateDebtSecuritiesMember
State And Municipal Tax-Exempt [Member]    
Securities [Line Items]    
Available-for-sale Securities, Fair Value, Total 2,967us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember
1,072us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember
Available-for-sale Securities, Unrealized Loss, Total (10)dnbf_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAggregateLossesAccumulatedInAoci
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember
(19)dnbf_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAggregateLossesAccumulatedInAoci
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember
Available-for-sale Securities, Fair Value Impaired Less Than 12 Months 2,360us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember
300us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember
Available-for-sale Securities, Unrealized Loss Less Than 12 Months (9)dnbf_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLossesAccumulatedInAoci
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember
(6)dnbf_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLossesAccumulatedInAoci
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember
Available-for-sale Securities, Fair Value Impaired More Than 12 Months 607us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember
772us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember
Available-for-sale Securities, Unrealized Loss More Than 12 Months (1)dnbf_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLossesAccumulatedInAoci
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember
(13)dnbf_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLossesAccumulatedInAoci
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember
Equity Securities [Member]    
Securities [Line Items]    
Available-for-sale Securities, Fair Value, Total 12us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_EquitySecuritiesMember
12us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_EquitySecuritiesMember
Available-for-sale Securities, Unrealized Loss, Total (11)dnbf_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAggregateLossesAccumulatedInAoci
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_EquitySecuritiesMember
(11)dnbf_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAggregateLossesAccumulatedInAoci
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_EquitySecuritiesMember
Available-for-sale Securities, Fair Value Impaired More Than 12 Months 12us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_EquitySecuritiesMember
12us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_EquitySecuritiesMember
Available-for-sale Securities, Unrealized Loss More Than 12 Months (11)dnbf_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLossesAccumulatedInAoci
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_EquitySecuritiesMember
(11)dnbf_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLossesAccumulatedInAoci
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_EquitySecuritiesMember
Collateralized Mortgage Obligations GSE [Member]    
Securities [Line Items]    
Held-to-maturity Securities, Fair Value, Total 3,043us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionFairValue
/ us-gaap_DebtSecurityAxis
= us-gaap_CollateralizedDebtObligationsMember
2,530us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionFairValue
/ us-gaap_DebtSecurityAxis
= us-gaap_CollateralizedDebtObligationsMember
Held-to-maturity Securities, Unrealized Losses (29)dnbf_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionAggregateLoss2
/ us-gaap_DebtSecurityAxis
= us-gaap_CollateralizedDebtObligationsMember
(89)dnbf_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionAggregateLoss2
/ us-gaap_DebtSecurityAxis
= us-gaap_CollateralizedDebtObligationsMember
Held-to-maturity Securities, Fair Value Impaired Less Than 12 Months 3,043us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
/ us-gaap_DebtSecurityAxis
= us-gaap_CollateralizedDebtObligationsMember
2,530us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
/ us-gaap_DebtSecurityAxis
= us-gaap_CollateralizedDebtObligationsMember
Held-to-maturity Securities, Unrealized Loss Less Than 12 Months (29)dnbf_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateAccumulatedLoss
/ us-gaap_DebtSecurityAxis
= us-gaap_CollateralizedDebtObligationsMember
(89)dnbf_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateAccumulatedLoss
/ us-gaap_DebtSecurityAxis
= us-gaap_CollateralizedDebtObligationsMember
State And Municipal Tax-Exempt [Member]    
Securities [Line Items]    
Held-to-maturity Securities, Fair Value, Total 19,054us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionFairValue
/ us-gaap_DebtSecurityAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember
29,142us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionFairValue
/ us-gaap_DebtSecurityAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember
Held-to-maturity Securities, Unrealized Losses (547)dnbf_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionAggregateLoss2
/ us-gaap_DebtSecurityAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember
(2,425)dnbf_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionAggregateLoss2
/ us-gaap_DebtSecurityAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember
Held-to-maturity Securities, Fair Value Impaired Less Than 12 Months 2,138us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
/ us-gaap_DebtSecurityAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember
17,434us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
/ us-gaap_DebtSecurityAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember
Held-to-maturity Securities, Unrealized Loss Less Than 12 Months (7)dnbf_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateAccumulatedLoss
/ us-gaap_DebtSecurityAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember
(727)dnbf_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateAccumulatedLoss
/ us-gaap_DebtSecurityAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value 16,916us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
/ us-gaap_DebtSecurityAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember
11,708us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
/ us-gaap_DebtSecurityAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses $ (540)dnbf_HeldToMaturitySecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateAccumulatedLoss
/ us-gaap_DebtSecurityAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember
$ (1,698)dnbf_HeldToMaturitySecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateAccumulatedLoss
/ us-gaap_DebtSecurityAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember