Loans and Allowance for Credit Losses - Aging in past due loans and nonaccrual status, with and without an ACL, by loan segment (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Aging of the recorded investment in past due loans by loan segment
Nonaccrual without ACL	$ 249	$ 919
Totals	3,784,205	3,724,282
Current
Aging of the recorded investment in past due loans by loan segment
Totals	3,783,956	3,708,253
30-89 Days Past Due
Aging of the recorded investment in past due loans by loan segment
Totals		15,110
Commercial
Aging of the recorded investment in past due loans by loan segment
Nonaccrual without ACL	175	95
Totals	483,069	464,061
Commercial \| Current
Aging of the recorded investment in past due loans by loan segment
Totals	482,894	463,966
Construction and Land Development
Aging of the recorded investment in past due loans by loan segment
Nonaccrual without ACL	74	80
Totals	200,970	232,804
Construction and Land Development \| Current
Aging of the recorded investment in past due loans by loan segment
Totals	200,896	232,724
1-4 Family Construction
Aging of the recorded investment in past due loans by loan segment
Nonaccrual without ACL		249
Totals	65,606	65,087
1-4 Family Construction \| Current
Aging of the recorded investment in past due loans by loan segment
Totals	65,606	64,838
1-4 Family Mortgage
Aging of the recorded investment in past due loans by loan segment
Totals	417,773	402,396
1-4 Family Mortgage \| Current
Aging of the recorded investment in past due loans by loan segment
Totals	417,773	402,396
Multifamily
Aging of the recorded investment in past due loans by loan segment
Totals	1,389,345	1,388,541
Multifamily \| Current
Aging of the recorded investment in past due loans by loan segment
Totals	1,389,345	1,373,431
Multifamily \| 30-89 Days Past Due
Aging of the recorded investment in past due loans by loan segment
Totals		15,110
CRE Owner Occupied
Aging of the recorded investment in past due loans by loan segment
Nonaccrual without ACL		494
Totals	182,589	175,783
CRE Owner Occupied \| Current
Aging of the recorded investment in past due loans by loan segment
Totals	182,589	175,289
CRE Non-owner Occupied
Aging of the recorded investment in past due loans by loan segment
Totals	1,035,702	987,306
CRE Non-owner Occupied \| Current
Aging of the recorded investment in past due loans by loan segment
Totals	1,035,702	987,306
Consumer and other
Aging of the recorded investment in past due loans by loan segment
Nonaccrual without ACL		1
Totals	9,151	8,304
Consumer and other \| Current
Aging of the recorded investment in past due loans by loan segment
Totals	$ 9,151	$ 8,303

Amortized cost excluding accrued interest, before allowance for credit loss, of financing receivable. Excludes net investment in lease.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479344/326-20-45-1

Reference 2: 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

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479319/326-20-50-5

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amortized cost of financing receivable on nonaccrual status with no allowance for credit loss. 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 16
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479319/326-20-50-16

+ Details

Name:	us-gaap_FinancingReceivableNonaccrualNoAllowance
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- 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/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479319/326-20-50-14

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 80
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479294/326-20-55-80

+ Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_FinancingReceivablesPeriodPastDueAxis=us-gaap_FinancialAssetNotPastDueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablesPeriodPastDueAxis=bwb_FinancingReceivables30To89DaysPastDueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=bwb_ConstructionAndLandDevelopmentPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=bwb_OneToFourFamilyConstructionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=bwb_OneToFourFamilyMortgageMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=bwb_MultiFamilyResidentialMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=bwb_CommercialRealEstateOwnerOccupiedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=bwb_CommercialRealEstateNonOwnerOccupiedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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