XML 52 R43.htm IDEA: XBRL DOCUMENT
v3.23.3

SECURITIES - Narrative (Details) - USD ($) | 3 Months Ended | 9 Months Ended | 12 Months Ended
--- | --- | --- | ---
Sep. 30, 2023 | Sep. 30, 2022 | Sep. 30, 2023 | Sep. 30, 2022 | Dec. 31, 2022
Securities available-for-sale: |  |  |  |  |
Transfer from securities held-to-maturity | $ 0 |  | $ 0 | $ 400,000,000.0 |
Securities available-for-sale transferred to held-to-maturity |  |  |  | 372,154,000 |
Unrealized loss on transfer of securities to held to maturity |  |  |  | (27,800,000) |
Gain (loss) on transfer of securities to held-to-maturity |  |  |  | 0 |
Transfers to or from securities held-to-maturity |  | $ 0 |  | 0 |
Securities held-to-maturity | $ 495,986,000 |  | $ 495,986,000 |  | $ 505,759,000
Number of holdings of securities of any one issuer in an amount greater than 10% of stockholders equity | 0 |  | 0 |  | 0
Threshold for disclosure percentage |  |  | 10.00% |  | 10.00%
Available for sale debt securities, unrealized loss position due to credit | $ 0 |  | $ 0 |  |
Allowance for credit losses on available for sale debt securities | 0 |  | 0 |  |
Accrued interest receivable on securities |  |  | 3,300,000 |  | $ 5,400,000
Unrealized losses are related to credit losses | 0 |  | 0 |  |
Securities pledged |  |  |  |  |
Securities available-for-sale: |  |  |  |  |
Carrying amount of securities pledged | $ 470,000,000.0 |  | $ 470,000,000.0 |  | $ 631,400,000
Financial Instrument, Owned, Pledged Status [Extensible Enumeration] | Securities pledged |  | Securities pledged |  | Securities pledged
Carrying Amount |  |  |  |  |
Securities available-for-sale: |  |  |  |  |
Securities held-to-maturity | $ 600,291,000 |  | $ 600,291,000 |  | $ 585,798,000
Fair Value |  |  |  |  |
Securities available-for-sale: |  |  |  |  |
Securities available-for-sale transferred to held-to-maturity |  |  |  | $ 372,200,000 |
Securities held-to-maturity | $ 495,986,000 |  | $ 495,986,000 |  | $ 505,759,000

X
- Definition Amount of gain (loss) recognized in earnings from transfer of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale) to investment in debt security measured at fair value amortized cost (held-to-maturity). + References No definition available. + Details
Name: | dcom_DebtSecuritiesAvailableForSaleTransferToHeldToMaturityGainLoss
Namespace Prefix: | dcom_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Represents the holdings of securities of any one issuer, other than the U.S. Government and its agencies, in an amount greater than 10% of stockholders equity. + References No definition available. + Details
Name: | dcom_HoldingsOfSecuritiesOfAnyOneIssuerGreaterThan10PercentOfStockholdersEquity
Namespace Prefix: | dcom_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition The amount of securities transferred to held to maturity. + References No definition available. + Details
Name: | dcom_SecuritiesTransferredToHeldToMaturity
Namespace Prefix: | dcom_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Threshold percentage which the entity uses for disclosure. + References No definition available. + Details
Name: | dcom_ThresholdForDisclosurePercentage
Namespace Prefix: | dcom_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition The amount of transfers of securities held-to-maturity to securities available-for-sale. + References No definition available. + Details
Name: | dcom_TransfersOfSecuritiesHeldToMaturityToSecuritiesAvailableForSale
Namespace Prefix: | dcom_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Represents the amount of transfers to or from securities held-to-maturity. + References No definition available. + Details
Name: | dcom_TransfersToOrFromSecuritiesHeldToMaturity
Namespace Prefix: | dcom_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Represents unrealized losses are related to credit losses. + References No definition available. + Details
Name: | dcom_UnrealizedLossesRelatedToCreditLosses
Namespace Prefix: | dcom_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount excluding accrued interest, of allowance for credit loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org//1943274/2147479130/326-30-45-1 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostAllowanceForCreditLossExcludingAccruedInterest
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position without allowance for credit loss. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 55 -Paragraph 8 -Publisher FASB -URI https://asc.fasb.org//1943274/2147479081/326-30-55-8 Reference 2: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Subparagraph (a)(1) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-6 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 4 -Subparagraph (a)(1) -Publisher FASB -URI https://asc.fasb.org//1943274/2147479106/326-30-50-4 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPosition
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The aggregate fair value as of the balance sheet date of financial instruments and other positions owned by the entity including: (1) mortgages, mortgage-backed and asset backed securities; (2) US government and agency obligations; (3) state and municipal government obligations; (4) other sovereign government debt; (5) corporate obligations; (6) corporate equities; (7) principal investments; (8) derivative contracts; and (9) physical commodities. Includes both pledged and unpledged holdings. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 940 -SubTopic 320 -Section 45 -Paragraph 2 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481961/940-320-45-2 + Details
Name: | us-gaap_FinancialInstrumentsOwnedAtFairValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Indicates pledged status of security from proprietary transaction entered into by broker-dealer for trading and investment purposes. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 860 -SubTopic 30 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481444/860-30-45-1 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 860 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 1A -Subparagraph (b)(2) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481420/860-30-50-1A Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (bb) -SubTopic 10 -Topic 810 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481203/810-10-50-3 Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef -Name Accounting Standards Codification -Section 45 -Paragraph 25 -Subparagraph (a) -SubTopic 10 -Topic 810 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481231/810-10-45-25 Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef -Name Accounting Standards Codification -Section 50 -Paragraph 1A -Subparagraph (b)(1)(i) -SubTopic 30 -Topic 860 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481420/860-30-50-1A + Details
Name: | us-gaap_FinancialInstrumentsOwnedPledgedStatusExtensibleEnumeration
Namespace Prefix: | us-gaap_
Data Type: | enum2:enumerationSetItemType
Balance Type: | na
Period Type: | instant

X
- Definition Fair value of investment in debt security measured at amortized cost (held-to-maturity). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(1)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147479440/944-210-S99-1 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 5A -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-5A Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(6)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147479853/942-210-S99-1 Reference 4: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Subparagraph (aa) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-5 + Details
Name: | us-gaap_HeldToMaturitySecuritiesFairValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount before accretion (amortization) of purchase discount (premium) of interest income on nonoperating securities. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 280 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 22 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org//1943274/2147482810/280-10-50-22 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 220 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.7(b)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147483621/220-10-S99-2 + Details
Name: | us-gaap_InvestmentIncomeInterest
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount, after tax, of adjustment from accumulated other comprehensive income (loss) for amortization of gain (loss) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale) from transfer to investment in debt security measured at amortized cost (held-to-maturity). + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 35 -Paragraph 10B -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481889/320-10-35-10B Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 220 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 14A -Publisher FASB -URI https://asc.fasb.org//1943274/2147482790/220-10-45-14A + Details
Name: | us-gaap_OciDebtSecuritiesAvailableForSaleTransferToHeldToMaturityAdjustmentFromAociForAmortizationOfGainLossAfterTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-2 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-2 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (aa) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-2 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (aaa) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-2 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-2 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-2 Reference 7: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-2 Reference 8: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-3 Reference 9: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-3 Reference 10: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-3 Reference 11: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-3 Reference 12: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-3 + Details
Name: | us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_PledgedStatusAxis=us-gaap_AssetPledgedAsCollateralMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByMeasurementBasisAxis=us-gaap_CarryingReportedAmountFairValueDisclosureMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByMeasurementBasisAxis=us-gaap_EstimateOfFairValueFairValueDisclosureMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |