XML 68 R58.htm IDEA: XBRL DOCUMENT
v3.24.3

LOANS HELD FOR INVESTMENT, NET - Credit Quality Indicators (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended | 12 Months Ended
--- | --- | --- | ---
Sep. 30, 2024 | Sep. 30, 2023 | Sep. 30, 2024 | Sep. 30, 2023 | Dec. 31, 2023
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
Total | $ 10,886,387 |  | $ 10,886,387 |  | $ 10,766,837
Pass |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
2024/2023 | 419,631 |  | 419,631 |  | 922,902
2023/2022 | 911,305 |  | 911,305 |  | 2,700,103
2022/2021 | 2,643,194 |  | 2,643,194 |  | 1,582,274
2021/2020 | 1,482,599 |  | 1,482,599 |  | 954,855
2020/2019 | 935,051 |  | 935,051 |  | 960,030
2019/2018 and Prior | 2,954,119 |  | 2,954,119 |  | 2,257,567
Revolving | 905,684 |  | 905,684 |  | 704,128
Revolving-Term | 87,373 |  | 87,373 |  | 60,048
Total | 10,338,956 |  | 10,338,956 |  | 10,141,907
Special Mention |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
2024/2023 | 141 |  | 141 |  | 481
2023/2022 | 531 |  | 531 |  | 53,182
2022/2021 | 17,876 |  | 17,876 |  | 45,366
2021/2020 | 32,339 |  | 32,339 |  | 92,825
2020/2019 | 92,249 |  | 92,249 |  | 27,827
2019/2018 and Prior | 111,019 |  | 111,019 |  | 70,219
Revolving | 17,266 |  | 17,266 |  | 21,267
Revolving-Term | 9,459 |  | 9,459 |  | 26,082
Total | 280,880 |  | 280,880 |  | 337,249
Substandard |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
2023/2022 | 335 |  | 335 |  | 1,857
2022/2021 | 9,039 |  | 9,039 |  | 2,196
2021/2020 | 21,804 |  | 21,804 |  | 96,805
2020/2019 | 65,772 |  | 65,772 |  | 14,483
2019/2018 and Prior | 124,464 |  | 124,464 |  | 130,103
Revolving | 6,798 |  | 6,798 |  | 15,567
Revolving-Term | 31,670 |  | 31,670 |  | 20,167
Total | 259,882 |  | 259,882 |  | 281,178
Doubtful |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
2019/2018 and Prior | 611 |  | 611 |  | 748
Total | 611 |  | 611 |  | 748
Business Loans |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
2024/2023 | 248,482 |  | 248,482 |  | 259,180
2023/2022 | 248,518 |  | 248,518 |  | 434,299
2022/2021 | 383,036 |  | 383,036 |  | 200,169
2021/2020 | 211,346 |  | 211,346 |  | 165,092
2020/2019 | 177,262 |  | 177,262 |  | 160,799
2019/2018 and Prior | 427,992 |  | 427,992 |  | 339,404
Revolving | 863,375 |  | 863,375 |  | 670,394
Revolving-Term | 91,718 |  | 91,718 |  | 78,834
Total | 2,651,729 |  | 2,651,729 |  | 2,308,171
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract] |  |  |  |  |
YTD Gross Charge-Offs 2022/2021 |  |  | 158 |  | 77
YTD Gross Charge-Offs 2021/2020 |  |  | 116 |  | 38
YTD Gross Charge-Offs 2020/2019 |  |  | 267 |  | 4,166
YTD Gross Charge-Offs 2019/2018 and Prior |  |  | 584 |  | 2,229
YTD Gross Charge-Offs Revolving |  |  |  |  | 5,464
YTD Gross Charge-Offs Revolving-Term |  |  | 3,940 |  | 3,390
YTD Gross Charge-Offs | 3,090 | $ 5,147 | 5,065 | $ 10,921 | 15,364
Business Loans | Pass |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
2024/2023 | 248,341 |  | 248,341 |  | 258,699
2023/2022 | 247,652 |  | 247,652 |  | 390,760
2022/2021 | 357,323 |  | 357,323 |  | 196,790
2021/2020 | 204,733 |  | 204,733 |  | 144,796
2020/2019 | 169,319 |  | 169,319 |  | 150,871
2019/2018 and Prior | 394,679 |  | 394,679 |  | 305,258
Revolving | 840,224 |  | 840,224 |  | 633,719
Revolving-Term | 52,024 |  | 52,024 |  | 35,079
Total | 2,514,295 |  | 2,514,295 |  | 2,115,972
Business Loans | Special Mention |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
2024/2023 | 141 |  | 141 |  | 481
2023/2022 | 531 |  | 531 |  | 41,682
2022/2021 | 16,674 |  | 16,674 |  | 1,199
2021/2020 | 4,318 |  | 4,318 |  | 13,567
2020/2019 | 3,090 |  | 3,090 |  | 7,125
2019/2018 and Prior | 10,468 |  | 10,468 |  | 3,150
Revolving | 17,107 |  | 17,107 |  | 21,108
Revolving-Term | 9,459 |  | 9,459 |  | 25,306
Total | 61,788 |  | 61,788 |  | 113,618
Business Loans | Substandard |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
2023/2022 | 335 |  | 335 |  | 1,857
2022/2021 | 9,039 |  | 9,039 |  | 2,180
2021/2020 | 2,295 |  | 2,295 |  | 6,729
2020/2019 | 4,853 |  | 4,853 |  | 2,803
2019/2018 and Prior | 22,234 |  | 22,234 |  | 30,248
Revolving | 6,044 |  | 6,044 |  | 15,567
Revolving-Term | 30,235 |  | 30,235 |  | 18,449
Total | 75,035 |  | 75,035 |  | 77,833
Business Loans | Doubtful |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
2019/2018 and Prior | 611 |  | 611 |  | 748
Total | 611 |  | 611 |  | 748
One-to-Four Family Residential and Cooperative/Condominium Apartment |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
2024/2023 | 93,307 |  | 93,307 |  | 170,601
2023/2022 | 162,376 |  | 162,376 |  | 213,479
2022/2021 | 206,691 |  | 206,691 |  | 102,684
2021/2020 | 98,996 |  | 98,996 |  | 70,529
2020/2019 | 65,503 |  | 65,503 |  | 62,693
2019/2018 and Prior | 266,891 |  | 266,891 |  | 221,875
Revolving | 28,630 |  | 28,630 |  | 31,364
Revolving-Term | 10,373 |  | 10,373 |  | 14,330
Total | 932,767 |  | 932,767 |  | 887,555
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract] |  |  |  |  |
YTD Gross Charge-Offs Revolving-Term |  |  |  |  | 14
YTD Gross Charge-Offs |  |  |  | 14 | 14
One-to-Four Family Residential and Cooperative/Condominium Apartment | Pass |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
2024/2023 | 93,307 |  | 93,307 |  | 170,601
2023/2022 | 162,376 |  | 162,376 |  | 213,479
2022/2021 | 206,691 |  | 206,691 |  | 102,684
2021/2020 | 98,996 |  | 98,996 |  | 69,524
2020/2019 | 64,514 |  | 64,514 |  | 62,356
2019/2018 and Prior | 257,747 |  | 257,747 |  | 213,131
Revolving | 27,717 |  | 27,717 |  | 31,205
Revolving-Term | 9,595 |  | 9,595 |  | 12,493
Total | 920,943 |  | 920,943 |  | 875,473
One-to-Four Family Residential and Cooperative/Condominium Apartment | Special Mention |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
2019/2018 and Prior | 719 |  | 719 |  | 33
Revolving | 159 |  | 159 |  | 159
Revolving-Term |  |  |  |  | 776
Total | 878 |  | 878 |  | 968
One-to-Four Family Residential and Cooperative/Condominium Apartment | Substandard |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
2021/2020 |  |  |  |  | 1,005
2020/2019 | 989 |  | 989 |  | 337
2019/2018 and Prior | 8,425 |  | 8,425 |  | 8,711
Revolving | 754 |  | 754 |  |
Revolving-Term | 778 |  | 778 |  | 1,061
Total | 10,946 |  | 10,946 |  | 11,114
Multifamily Residential and Residential Mixed-Use |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
2024/2023 | 21,942 |  | 21,942 |  | 256,822
2023/2022 | 254,215 |  | 254,215 |  | 1,340,197
2022/2021 | 1,319,836 |  | 1,319,836 |  | 587,686
2021/2020 | 561,366 |  | 561,366 |  | 316,312
2020/2019 | 302,652 |  | 302,652 |  | 393,912
2019/2018 and Prior | 1,397,202 |  | 1,397,202 |  | 1,113,081
Revolving | 3,892 |  | 3,892 |  | 4,841
Revolving-Term | 5,373 |  | 5,373 |  | 4,325
Total | 3,866,478 |  | 3,866,478 |  | 4,017,176
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract] |  |  |  |  |
YTD Gross Charge-Offs 2020/2019 |  |  | 1,292 |  |
YTD Gross Charge-Offs 2019/2018 and Prior |  |  | 2,553 |  | 2
YTD Gross Charge-Offs | 1,294 | 2 | 3,845 | 2 | 2
Multifamily Residential and Residential Mixed-Use | Pass |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
2024/2023 | 21,942 |  | 21,942 |  | 256,822
2023/2022 | 254,215 |  | 254,215 |  | 1,340,197
2022/2021 | 1,318,634 |  | 1,318,634 |  | 578,352
2021/2020 | 548,979 |  | 548,979 |  | 283,633
2020/2019 | 288,401 |  | 288,401 |  | 384,937
2019/2018 and Prior | 1,259,803 |  | 1,259,803 |  | 981,820
Revolving | 3,892 |  | 3,892 |  | 4,841
Revolving-Term | 5,373 |  | 5,373 |  | 4,325
Total | 3,701,239 |  | 3,701,239 |  | 3,834,927
Multifamily Residential and Residential Mixed-Use | Special Mention |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
2022/2021 | 1,202 |  | 1,202 |  | 9,334
2021/2020 | 12,387 |  | 12,387 |  | 3,880
2020/2019 | 14,251 |  | 14,251 |  | 3,886
2019/2018 and Prior | 73,409 |  | 73,409 |  | 64,273
Total | 101,249 |  | 101,249 |  | 81,373
Multifamily Residential and Residential Mixed-Use | Substandard |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
2021/2020 |  |  |  |  | 28,799
2020/2019 |  |  |  |  | 5,089
2019/2018 and Prior | 63,990 |  | 63,990 |  | 66,988
Total | 63,990 |  | 63,990 |  | 100,876
Non-Owner-Occupied Commercial Real Estate |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
2024/2023 | 45,208 |  | 45,208 |  | 220,045
2023/2022 | 216,058 |  | 216,058 |  | 738,133
2022/2021 | 728,276 |  | 728,276 |  | 665,134
2021/2020 | 626,752 |  | 626,752 |  | 582,652
2020/2019 | 547,655 |  | 547,655 |  | 370,018
2019/2018 and Prior | 1,095,528 |  | 1,095,528 |  | 783,840
Revolving | 12,328 |  | 12,328 |  | 11,919
Revolving-Term | 8,251 |  | 8,251 |  | 7,926
Total | 3,280,056 |  | 3,280,056 |  | 3,379,667
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract] |  |  |  |  |
YTD Gross Charge-Offs Revolving-Term |  |  | 96 |  |
YTD Gross Charge-Offs | 96 |  | 96 |  |
Non-Owner-Occupied Commercial Real Estate | Pass |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
2024/2023 | 45,208 |  | 45,208 |  | 220,045
2023/2022 | 216,058 |  | 216,058 |  | 738,133
2022/2021 | 728,276 |  | 728,276 |  | 645,246
2021/2020 | 606,580 |  | 606,580 |  | 447,002
2020/2019 | 412,817 |  | 412,817 |  | 359,201
2019/2018 and Prior | 1,039,290 |  | 1,039,290 |  | 756,921
Revolving | 12,328 |  | 12,328 |  | 11,919
Revolving-Term | 8,251 |  | 8,251 |  | 7,926
Total | 3,068,808 |  | 3,068,808 |  | 3,186,393
Non-Owner-Occupied Commercial Real Estate | Special Mention |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
2022/2021 |  |  |  |  | 19,872
2021/2020 | 663 |  | 663 |  | 75,378
2020/2019 | 74,908 |  | 74,908 |  | 4,563
2019/2018 and Prior | 26,423 |  | 26,423 |  | 2,763
Total | 101,994 |  | 101,994 |  | 102,576
Non-Owner-Occupied Commercial Real Estate | Substandard |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
2022/2021 |  |  |  |  | 16
2021/2020 | 19,509 |  | 19,509 |  | 60,272
2020/2019 | 59,930 |  | 59,930 |  | 6,254
2019/2018 and Prior | 29,815 |  | 29,815 |  | 24,156
Total | 109,254 |  | 109,254 |  | 90,698
Non-Owner-Occupied Commercial Real Estate | Real estate loan |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
Total | 3,280,056 |  | 3,280,056 |  | 3,379,667
Acquisition, development, and construction ("ADC") |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
2024/2023 | 10,833 |  | 10,833 |  | 16,735
2023/2022 | 31,004 |  | 31,004 |  | 29,034
2022/2021 | 32,270 |  | 32,270 |  | 74,163
2021/2020 | 38,282 |  | 38,282 |  | 9,900
2020/2019 |  |  |  |  | 14,918
2019/2018 and Prior | 2,600 |  | 2,600 |  | 437
Revolving | 21,523 |  | 21,523 |  | 22,444
Revolving-Term | 12,787 |  | 12,787 |  | 882
Total | 149,299 |  | 149,299 |  | 168,513
Acquisition, development, and construction ("ADC") | Pass |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
2024/2023 | 10,833 |  | 10,833 |  | 16,735
2023/2022 | 31,004 |  | 31,004 |  | 17,534
2022/2021 | 32,270 |  | 32,270 |  | 59,202
2021/2020 | 23,311 |  | 23,311 |  | 9,900
2020/2019 |  |  |  |  | 2,665
2019/2018 and Prior | 2,600 |  | 2,600 |  | 437
Revolving | 21,523 |  | 21,523 |  | 22,444
Revolving-Term | 12,130 |  | 12,130 |  | 225
Total | 133,671 |  | 133,671 |  | 129,142
Acquisition, development, and construction ("ADC") | Special Mention |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
2023/2022 |  |  |  |  | 11,500
2022/2021 |  |  |  |  | 14,961
2021/2020 | 14,971 |  | 14,971 |  |
2020/2019 |  |  |  |  | 12,253
Total | 14,971 |  | 14,971 |  | 38,714
Acquisition, development, and construction ("ADC") | Substandard |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
Revolving-Term | 657 |  | 657 |  | 657
Total | 657 |  | 657 |  | 657
Other Loans |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
Total | 6,058 |  | 6,058 |  | 5,755
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract] |  |  |  |  |
YTD Gross Charge-Offs | 14 | $ 26 | 59 | $ 60 |
Other Loans | Credit Risk Profile |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
Total | 6,058 |  | 6,058 |  | 5,755
Other Loans | Performing | Credit Risk Profile |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
Total | 6,052 |  | 6,052 |  | 5,755
Other Loans | Non-accrual | Credit Risk Profile |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
Total | 6 |  | 6 |  |
Excludes Other Loans |  |  |  |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |  |  |  |
2024/2023 | 419,772 |  | 419,772 |  | 923,383
2023/2022 | 912,171 |  | 912,171 |  | 2,755,142
2022/2021 | 2,670,109 |  | 2,670,109 |  | 1,629,836
2021/2020 | 1,536,742 |  | 1,536,742 |  | 1,144,485
2020/2019 | 1,093,072 |  | 1,093,072 |  | 1,002,340
2019/2018 and Prior | 3,190,213 |  | 3,190,213 |  | 2,458,637
Revolving | 929,748 |  | 929,748 |  | 740,962
Revolving-Term | 128,502 |  | 128,502 |  | 106,297
Total | $ 10,880,329 |  | 10,880,329 |  | 10,761,082
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract] |  |  |  |  |
YTD Gross Charge-Offs 2022/2021 |  |  | 158 |  | 77
YTD Gross Charge-Offs 2021/2020 |  |  | 116 |  | 38
YTD Gross Charge-Offs 2020/2019 |  |  | 1,559 |  | 4,166
YTD Gross Charge-Offs 2019/2018 and Prior |  |  | 3,137 |  | 2,231
YTD Gross Charge-Offs Revolving |  |  |  |  | 5,464
YTD Gross Charge-Offs Revolving-Term |  |  | 4,036 |  | 3,404
YTD Gross Charge-Offs |  |  | $ 9,006 |  | $ 15,380

X
- References No definition available. + Details
Name: | dcom_CreditRiskProfileRealEstateLoansAbstract
Namespace Prefix: | dcom_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount, excluding accrued interest, of decrease in allowance for credit loss on financing receivable from writeoff. Excludes net investment in lease. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-6 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 13 -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-13 + Details
Name: | us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoffByOriginationYearAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amortized cost excluding accrued interest, before allowance for credit loss, fee, and loan in process, of financing receivable. Excludes net investment in lease. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(7)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1 + Details
Name: | us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcess
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amortized cost excluding accrued interest, of financing receivable originated more than five years prior to current fiscal year. Excludes net investment in lease. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 79 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479294/326-20-55-79 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-6 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 3B -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-3B + Details
Name: | us-gaap_FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYear
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount, excluding accrued interest, of writeoff of financing receivable originated more than five years before current fiscal year. Excludes net investment in lease. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-6 + Details
Name: | us-gaap_FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYearWriteoff
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amortized cost excluding accrued interest, of financing receivable that can be withdrawn, repaid, and redrawn. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 79 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479294/326-20-55-79 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-6 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 3B -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-3B + Details
Name: | us-gaap_FinancingReceivableExcludingAccruedInterestRevolving
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amortized cost excluding accrued interest, of revolving financing receivable converted to term loan. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 79 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479294/326-20-55-79 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 6A -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-6A Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 3B -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-3B + Details
Name: | us-gaap_FinancingReceivableExcludingAccruedInterestRevolvingConvertedToTermLoan
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount, excluding accrued interest, of writeoff of revolving financing receivable converted to term loan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 6A -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-6A + Details
Name: | us-gaap_FinancingReceivableExcludingAccruedInterestRevolvingConvertedToTermLoanWriteoff
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount, excluding accrued interest, of writeoff of financing receivable that can be withdrawn, repaid, and redrawn. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-6 + Details
Name: | us-gaap_FinancingReceivableExcludingAccruedInterestRevolvingWriteoff
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amortized cost excluding accrued interest, of financing receivable originated four years prior to current fiscal year. Excludes net investment in lease. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 79 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479294/326-20-55-79 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-6 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 3B -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-3B + Details
Name: | us-gaap_FinancingReceivableExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYear
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount, excluding accrued interest, of writeoff of financing receivable originated four years before current fiscal year. Excludes net investment in lease. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-6 + Details
Name: | us-gaap_FinancingReceivableExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYearWriteoff
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amortized cost excluding accrued interest, of financing receivable originated three years prior to current fiscal year. Excludes net investment in lease. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 79 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479294/326-20-55-79 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-6 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 3B -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-3B + Details
Name: | us-gaap_FinancingReceivableExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYear
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount, excluding accrued interest, of writeoff of financing receivable originated three years before current fiscal year. Excludes net investment in lease. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-6 + Details
Name: | us-gaap_FinancingReceivableExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYearWriteoff
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amortized cost excluding accrued interest, of financing receivable originated in current fiscal year. Excludes net investment in lease. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 79 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479294/326-20-55-79 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-6 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 3B -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-3B + Details
Name: | us-gaap_FinancingReceivableExcludingAccruedInterestYearOneOriginatedCurrentFiscalYear
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amortized cost excluding accrued interest, of financing receivable originated two years prior to current fiscal year. Excludes net investment in lease. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 79 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479294/326-20-55-79 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-6 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 3B -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-3B + Details
Name: | us-gaap_FinancingReceivableExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYear
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount, excluding accrued interest, of writeoff of financing receivable originated two years before current fiscal year. Excludes net investment in lease. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-6 + Details
Name: | us-gaap_FinancingReceivableExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYearWriteoff
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amortized cost excluding accrued interest of financing receivable originated in fiscal year prior to current fiscal year. Excludes net investment in lease. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 79 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479294/326-20-55-79 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-6 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 3B -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-3B + Details
Name: | us-gaap_FinancingReceivableExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeCurrentFiscalYear
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_InternalCreditAssessmentAxis=us-gaap_PassMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InternalCreditAssessmentAxis=us-gaap_SpecialMentionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InternalCreditAssessmentAxis=us-gaap_SubstandardMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InternalCreditAssessmentAxis=us-gaap_DoubtfulMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivablePortfolioSegmentAxis=dcom_BusinessLoanPortfolioSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivablePortfolioSegmentAxis=dcom_OneToFourFamilyResidentialAndCooperativeUnitAllowanceMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivablePortfolioSegmentAxis=dcom_MultifamilyResidentialAndResidentialMixedUseAllowanceMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivablePortfolioSegmentAxis=dcom_NonOwnerOccupiedCommercialRealEstatePortfolioSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_RealEstateLoanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivablePortfolioSegmentAxis=dcom_AcquisitionDevelopmentAndConstructionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ConsumerPortfolioSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ManagingRisksInherentInServicingAssetsAndServicingLiabilitiesByTypeOfRiskAxis=us-gaap_CreditRiskMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentPerformanceStatusAxis=us-gaap_PerformingFinancingReceivableMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentPerformanceStatusAxis=us-gaap_NonperformingFinancingReceivableMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivablePortfolioSegmentAxis=dcom_ExcludesOtherLoansMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |