XML 116 R60.htm IDEA: XBRL DOCUMENT v2.4.1.9
ALLOWANCE FOR LOAN LOSSES AND RESERVE FOR FIRST LOSS POSITION (Details) (USD $)
In Thousands, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Financing Receivable, Allowance for Credit Losses [Line Items]      
Non-Impaired Substandard Component of the Allowance for Loans Losses $ 371dcom_NonImpairedSubstandardComponentOfAllowanceForLoansLosses $ 53dcom_NonImpairedSubstandardComponentOfAllowanceForLoansLosses  
Financing Receivable Allowance for credit losses, Special mention loans 228dcom_FinancingReceivableAllowanceForCreditLossesSpecialMentionLoans 185dcom_FinancingReceivableAllowanceForCreditLossesSpecialMentionLoans  
Increase (Decrease) in the balance of Substandard non impaired loans 12,755dcom_IncreaseDecreaseInBalanceOfSubstandardNonImpairedLoans    
One To Four Family Residential And Cooperative Unit Allowance [Member]      
Financing Receivable, Allowance for Credit Losses [Roll Forward]      
Beginning Balance 236us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_OneToFourFamilyResidentialAndCooperativeUnitAllowanceMember
344us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_OneToFourFamilyResidentialAndCooperativeUnitAllowanceMember
480us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_OneToFourFamilyResidentialAndCooperativeUnitAllowanceMember
Provision (credit) for loan losses (164)us-gaap_ProvisionForLoanLeaseAndOtherLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_OneToFourFamilyResidentialAndCooperativeUnitAllowanceMember
(187)us-gaap_ProvisionForLoanLeaseAndOtherLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_OneToFourFamilyResidentialAndCooperativeUnitAllowanceMember
624us-gaap_ProvisionForLoanLeaseAndOtherLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_OneToFourFamilyResidentialAndCooperativeUnitAllowanceMember
Charge-offs (46)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_OneToFourFamilyResidentialAndCooperativeUnitAllowanceMember
(117)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_OneToFourFamilyResidentialAndCooperativeUnitAllowanceMember
(777)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_OneToFourFamilyResidentialAndCooperativeUnitAllowanceMember
Recoveries 124us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_OneToFourFamilyResidentialAndCooperativeUnitAllowanceMember
196us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_OneToFourFamilyResidentialAndCooperativeUnitAllowanceMember
17us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_OneToFourFamilyResidentialAndCooperativeUnitAllowanceMember
Transfer from (to) reserve for loan Commitments     0dcom_FinancingReceivableAllowanceForCreditLossesTransfers
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_OneToFourFamilyResidentialAndCooperativeUnitAllowanceMember
Ending Balance 150us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_OneToFourFamilyResidentialAndCooperativeUnitAllowanceMember
236us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_OneToFourFamilyResidentialAndCooperativeUnitAllowanceMember
344us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_OneToFourFamilyResidentialAndCooperativeUnitAllowanceMember
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]      
Loans, Individually Evaluated for Impairment 605us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_OneToFourFamilyResidentialAndCooperativeUnitAllowanceMember
1,199us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_OneToFourFamilyResidentialAndCooperativeUnitAllowanceMember
1,291us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_OneToFourFamilyResidentialAndCooperativeUnitAllowanceMember
Loans, Collectively Evaluated for Impairment 72,895us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_OneToFourFamilyResidentialAndCooperativeUnitAllowanceMember
72,757us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_OneToFourFamilyResidentialAndCooperativeUnitAllowanceMember
90,585us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_OneToFourFamilyResidentialAndCooperativeUnitAllowanceMember
Allowance for Credit Losses, Individually Evaluated for Impairment 0us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_OneToFourFamilyResidentialAndCooperativeUnitAllowanceMember
0us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_OneToFourFamilyResidentialAndCooperativeUnitAllowanceMember
7us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_OneToFourFamilyResidentialAndCooperativeUnitAllowanceMember
Allowance for Credit Losses, Collectively Evaluated for Impairment 150us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_OneToFourFamilyResidentialAndCooperativeUnitAllowanceMember
236us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_OneToFourFamilyResidentialAndCooperativeUnitAllowanceMember
337us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_OneToFourFamilyResidentialAndCooperativeUnitAllowanceMember
Multifamily Residential And Residential Mixed Use Allowance [Member]      
Financing Receivable, Allowance for Credit Losses [Roll Forward]      
Beginning Balance 13,840us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MultifamilyResidentialAndResidentialMixedUseAllowanceMember
14,299us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MultifamilyResidentialAndResidentialMixedUseAllowanceMember
14,313us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MultifamilyResidentialAndResidentialMixedUseAllowanceMember
Provision (credit) for loan losses (76)us-gaap_ProvisionForLoanLeaseAndOtherLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MultifamilyResidentialAndResidentialMixedUseAllowanceMember
10us-gaap_ProvisionForLoanLeaseAndOtherLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MultifamilyResidentialAndResidentialMixedUseAllowanceMember
1,583us-gaap_ProvisionForLoanLeaseAndOtherLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MultifamilyResidentialAndResidentialMixedUseAllowanceMember
Charge-offs (87)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MultifamilyResidentialAndResidentialMixedUseAllowanceMember
(504)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MultifamilyResidentialAndResidentialMixedUseAllowanceMember
(2,478)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MultifamilyResidentialAndResidentialMixedUseAllowanceMember
Recoveries 175us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MultifamilyResidentialAndResidentialMixedUseAllowanceMember
35us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MultifamilyResidentialAndResidentialMixedUseAllowanceMember
829us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MultifamilyResidentialAndResidentialMixedUseAllowanceMember
Transfer from (to) reserve for loan Commitments     52dcom_FinancingReceivableAllowanceForCreditLossesTransfers
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MultifamilyResidentialAndResidentialMixedUseAllowanceMember
Ending Balance 13,852us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MultifamilyResidentialAndResidentialMixedUseAllowanceMember
13,840us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MultifamilyResidentialAndResidentialMixedUseAllowanceMember
14,299us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MultifamilyResidentialAndResidentialMixedUseAllowanceMember
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]      
Loans, Individually Evaluated for Impairment 1,272us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MultifamilyResidentialAndResidentialMixedUseAllowanceMember
2,345us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MultifamilyResidentialAndResidentialMixedUseAllowanceMember
2,460us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MultifamilyResidentialAndResidentialMixedUseAllowanceMember
Loans, Collectively Evaluated for Impairment 3,297,176us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MultifamilyResidentialAndResidentialMixedUseAllowanceMember
2,920,205us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MultifamilyResidentialAndResidentialMixedUseAllowanceMember
2,673,909us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MultifamilyResidentialAndResidentialMixedUseAllowanceMember
Allowance for Credit Losses, Individually Evaluated for Impairment 0us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MultifamilyResidentialAndResidentialMixedUseAllowanceMember
0us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MultifamilyResidentialAndResidentialMixedUseAllowanceMember
0us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MultifamilyResidentialAndResidentialMixedUseAllowanceMember
Allowance for Credit Losses, Collectively Evaluated for Impairment 13,852us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MultifamilyResidentialAndResidentialMixedUseAllowanceMember
13,840us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MultifamilyResidentialAndResidentialMixedUseAllowanceMember
14,299us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MultifamilyResidentialAndResidentialMixedUseAllowanceMember
Commercial Mixed Use Real Estate Allowance [Member]      
Financing Receivable, Allowance for Credit Losses [Roll Forward]      
Beginning Balance 3,003us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MixedUseCommercialRealEstateAllowanceMember
2,474us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MixedUseCommercialRealEstateAllowanceMember
1,528us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MixedUseCommercialRealEstateAllowanceMember
Provision (credit) for loan losses (1,710)us-gaap_ProvisionForLoanLeaseAndOtherLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MixedUseCommercialRealEstateAllowanceMember
891us-gaap_ProvisionForLoanLeaseAndOtherLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MixedUseCommercialRealEstateAllowanceMember
1,744us-gaap_ProvisionForLoanLeaseAndOtherLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MixedUseCommercialRealEstateAllowanceMember
Charge-offs (30)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MixedUseCommercialRealEstateAllowanceMember
(391)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MixedUseCommercialRealEstateAllowanceMember
(821)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MixedUseCommercialRealEstateAllowanceMember
Recoveries 381us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MixedUseCommercialRealEstateAllowanceMember
29us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MixedUseCommercialRealEstateAllowanceMember
18us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MixedUseCommercialRealEstateAllowanceMember
Transfer from (to) reserve for loan Commitments     5dcom_FinancingReceivableAllowanceForCreditLossesTransfers
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MixedUseCommercialRealEstateAllowanceMember
Ending Balance 1,644us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MixedUseCommercialRealEstateAllowanceMember
3,003us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MixedUseCommercialRealEstateAllowanceMember
2,474us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MixedUseCommercialRealEstateAllowanceMember
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]      
Loans, Individually Evaluated for Impairment 4,400us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MixedUseCommercialRealEstateAllowanceMember
4,400us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MixedUseCommercialRealEstateAllowanceMember
1,900us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MixedUseCommercialRealEstateAllowanceMember
Loans, Collectively Evaluated for Impairment 324,267us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MixedUseCommercialRealEstateAllowanceMember
371,510us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MixedUseCommercialRealEstateAllowanceMember
338,233us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MixedUseCommercialRealEstateAllowanceMember
Allowance for Credit Losses, Individually Evaluated for Impairment 0us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MixedUseCommercialRealEstateAllowanceMember
1,320us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MixedUseCommercialRealEstateAllowanceMember
0us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MixedUseCommercialRealEstateAllowanceMember
Allowance for Credit Losses, Collectively Evaluated for Impairment 1,644us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MixedUseCommercialRealEstateAllowanceMember
1,683us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MixedUseCommercialRealEstateAllowanceMember
2,474us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_MixedUseCommercialRealEstateAllowanceMember
Consumer Loan [Member]      
Financing Receivable, Allowance for Credit Losses [Roll Forward]      
Beginning Balance 24us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
27us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
26us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
Provision (credit) for loan losses 9us-gaap_ProvisionForLoanLeaseAndOtherLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
18us-gaap_ProvisionForLoanLeaseAndOtherLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
11us-gaap_ProvisionForLoanLeaseAndOtherLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
Charge-offs (9)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
(21)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
(10)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
Recoveries 0us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
0us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
0us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
Transfer from (to) reserve for loan Commitments     0dcom_FinancingReceivableAllowanceForCreditLossesTransfers
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
Ending Balance 24us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
24us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
27us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]      
Loans, Individually Evaluated for Impairment 0us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
0us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
0us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
Loans, Collectively Evaluated for Impairment 1,829us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
2,139us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
2,423us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
Allowance for Credit Losses, Individually Evaluated for Impairment 0us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
0us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
0us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
Allowance for Credit Losses, Collectively Evaluated for Impairment 24us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
24us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
27us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
Commercial Real Estate [Member]      
Financing Receivable, Allowance for Credit Losses [Roll Forward]      
Beginning Balance 3,047us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
3,382us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
3,783us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
Provision (credit) for loan losses 72us-gaap_ProvisionForLoanLeaseAndOtherLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
(342)us-gaap_ProvisionForLoanLeaseAndOtherLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
56us-gaap_ProvisionForLoanLeaseAndOtherLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
Charge-offs (306)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
(9)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
(521)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
Recoveries 10us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
16us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
39us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
Transfer from (to) reserve for loan Commitments     25dcom_FinancingReceivableAllowanceForCreditLossesTransfers
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
Ending Balance 2,823us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
3,047us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
3,382us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]      
Loans, Individually Evaluated for Impairment 13,707us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
22,245us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
47,493us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
Loans, Collectively Evaluated for Impairment 403,089us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
302,451us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
347,038us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
Allowance for Credit Losses, Individually Evaluated for Impairment 19us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
451us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
513us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
Allowance for Credit Losses, Collectively Evaluated for Impairment 2,804us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
2,596us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
2,869us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
Construction [Member]      
Financing Receivable, Allowance for Credit Losses [Roll Forward]      
Beginning Balance 3us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_ConstructionLoanReceivableAllowanceMember
24us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_ConstructionLoanReceivableAllowanceMember
124us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_ConstructionLoanReceivableAllowanceMember
Provision (credit) for loan losses (3)us-gaap_ProvisionForLoanLeaseAndOtherLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_ConstructionLoanReceivableAllowanceMember
(21)us-gaap_ProvisionForLoanLeaseAndOtherLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_ConstructionLoanReceivableAllowanceMember
(97)us-gaap_ProvisionForLoanLeaseAndOtherLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_ConstructionLoanReceivableAllowanceMember
Charge-offs 0us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_ConstructionLoanReceivableAllowanceMember
0us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_ConstructionLoanReceivableAllowanceMember
(3)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_ConstructionLoanReceivableAllowanceMember
Recoveries 0us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_ConstructionLoanReceivableAllowanceMember
0us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_ConstructionLoanReceivableAllowanceMember
0us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_ConstructionLoanReceivableAllowanceMember
Transfer from (to) reserve for loan Commitments     0dcom_FinancingReceivableAllowanceForCreditLossesTransfers
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_ConstructionLoanReceivableAllowanceMember
Ending Balance 0us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_ConstructionLoanReceivableAllowanceMember
3us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_ConstructionLoanReceivableAllowanceMember
24us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_ConstructionLoanReceivableAllowanceMember
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]      
Loans, Individually Evaluated for Impairment 0us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_ConstructionLoanReceivableAllowanceMember
0us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_ConstructionLoanReceivableAllowanceMember
0us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_ConstructionLoanReceivableAllowanceMember
Loans, Collectively Evaluated for Impairment 0us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_ConstructionLoanReceivableAllowanceMember
268us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_ConstructionLoanReceivableAllowanceMember
476us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_ConstructionLoanReceivableAllowanceMember
Allowance for Credit Losses, Individually Evaluated for Impairment 0us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_ConstructionLoanReceivableAllowanceMember
0us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_ConstructionLoanReceivableAllowanceMember
0us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_ConstructionLoanReceivableAllowanceMember
Allowance for Credit Losses, Collectively Evaluated for Impairment 0us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_ConstructionLoanReceivableAllowanceMember
3us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_ConstructionLoanReceivableAllowanceMember
24us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_ConstructionLoanReceivableAllowanceMember
Total Real Estate [Member]      
Financing Receivable, Allowance for Credit Losses [Roll Forward]      
Beginning Balance 20,129us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_TotalRealEstateReceivableMember
20,523us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_TotalRealEstateReceivableMember
20,228us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_TotalRealEstateReceivableMember
Provision (credit) for loan losses (1,881)us-gaap_ProvisionForLoanLeaseAndOtherLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_TotalRealEstateReceivableMember
351us-gaap_ProvisionForLoanLeaseAndOtherLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_TotalRealEstateReceivableMember
3,910us-gaap_ProvisionForLoanLeaseAndOtherLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_TotalRealEstateReceivableMember
Charge-offs (469)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_TotalRealEstateReceivableMember
(1,021)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_TotalRealEstateReceivableMember
(4,600)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_TotalRealEstateReceivableMember
Recoveries 690us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_TotalRealEstateReceivableMember
276us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_TotalRealEstateReceivableMember
903us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_TotalRealEstateReceivableMember
Transfer from (to) reserve for loan Commitments     82dcom_FinancingReceivableAllowanceForCreditLossesTransfers
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_TotalRealEstateReceivableMember
Ending Balance 18,469us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_TotalRealEstateReceivableMember
20,129us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_TotalRealEstateReceivableMember
20,523us-gaap_FinancingReceivableAllowanceForCreditLosses
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_TotalRealEstateReceivableMember
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]      
Loans, Individually Evaluated for Impairment 19,984us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_TotalRealEstateReceivableMember
30,189us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_TotalRealEstateReceivableMember
53,144us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_TotalRealEstateReceivableMember
Loans, Collectively Evaluated for Impairment 4,097,427us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_TotalRealEstateReceivableMember
3,667,191us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_TotalRealEstateReceivableMember
3,450,241us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_TotalRealEstateReceivableMember
Allowance for Credit Losses, Individually Evaluated for Impairment 19us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_TotalRealEstateReceivableMember
1,771us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_TotalRealEstateReceivableMember
520us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_TotalRealEstateReceivableMember
Allowance for Credit Losses, Collectively Evaluated for Impairment $ 18,450us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_TotalRealEstateReceivableMember
$ 18,358us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_TotalRealEstateReceivableMember
$ 20,003us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= dcom_TotalRealEstateReceivableMember