Loans and Allowance for Credit Losses - Allowance for loan losses by segment (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024
Allowance for Credit Losses for Loans and Leases:
Beginning Balance	$ 52,277	$ 50,494	$ 50,494
Provision for (Recovery of) Credit Losses on Loans and Leases	1,500	850
Loans and Leases Charged-off	(12)	(2)
Recoveries of Loans	1	5
Total Ending Allowance Balance	53,766	51,347	52,277
Allowance for loan losses and the recorded investment
Allowance for Loan Losses and Loans, Individually Evaluated for Credit Loss	2,031		144
Allowance for Loan Losses and Loans, Collectively Evaluated for Credit Loss	51,735		52,133
Loans and Leases Receivable, Allowance, Total	53,766	51,347	52,277
Loans, Individually Evaluated for Credit Loss	34,482		24,699
Loans, Collectively Evaluated for Credit Loss	3,985,594		3,843,815
Totals	4,020,076		3,868,514
Commercial
Allowance for Credit Losses for Loans and Leases:
Beginning Balance	5,630	5,398	5,398
Provision for (Recovery of) Credit Losses on Loans and Leases	217	206
Recoveries of Loans		3
Total Ending Allowance Balance	5,847	5,607	5,630
Allowance for loan losses and the recorded investment
Allowance for Loan Losses and Loans, Individually Evaluated for Credit Loss	288		133
Allowance for Loan Losses and Loans, Collectively Evaluated for Credit Loss	5,559		5,497
Loans and Leases Receivable, Allowance, Total	5,847	5,607	5,630
Loans, Individually Evaluated for Credit Loss	14,138		14,045
Loans, Collectively Evaluated for Credit Loss	514,663		483,617
Totals	528,801		497,662
Leases
Allowance for Credit Losses for Loans and Leases:
Beginning Balance	368
Provision for (Recovery of) Credit Losses on Loans and Leases	(3)
Total Ending Allowance Balance	365		368
Allowance for loan losses and the recorded investment
Allowance for Loan Losses and Loans, Individually Evaluated for Credit Loss	6		6
Allowance for Loan Losses and Loans, Collectively Evaluated for Credit Loss	359		362
Loans and Leases Receivable, Allowance, Total	365		368
Loans, Individually Evaluated for Credit Loss	34		34
Loans, Collectively Evaluated for Credit Loss	43,924		44,257
Totals	43,958		44,291
Construction and Land Development
Allowance for Credit Losses for Loans and Leases:
Beginning Balance	866	2,156	2,156
Provision for (Recovery of) Credit Losses on Loans and Leases	209	(328)
Total Ending Allowance Balance	1,075	1,828	866
Allowance for loan losses and the recorded investment
Allowance for Loan Losses and Loans, Collectively Evaluated for Credit Loss	1,075		866
Loans and Leases Receivable, Allowance, Total	1,075	1,828	866
Loans, Individually Evaluated for Credit Loss	52		58
Loans, Collectively Evaluated for Credit Loss	128,021		97,197
Totals	128,073		97,255
1-4 Family Construction
Allowance for Credit Losses for Loans and Leases:
Beginning Balance	331	558	558
Provision for (Recovery of) Credit Losses on Loans and Leases	(39)	19
Total Ending Allowance Balance	292	577	331
Allowance for loan losses and the recorded investment
Allowance for Loan Losses and Loans, Collectively Evaluated for Credit Loss	292		331
Loans and Leases Receivable, Allowance, Total	292	577	331
Loans, Collectively Evaluated for Credit Loss	39,438		41,961
Totals	39,438		41,961
Real Estate Mortgage
Allowance for Credit Losses for Loans and Leases:
Beginning Balance	44,940	42,277	42,277
Provision for (Recovery of) Credit Losses on Loans and Leases	1,112	946
Recoveries of Loans		1
Total Ending Allowance Balance	46,052	43,224	44,940
Allowance for loan losses and the recorded investment
Allowance for Loan Losses and Loans, Individually Evaluated for Credit Loss	1,737
Allowance for Loan Losses and Loans, Collectively Evaluated for Credit Loss	44,315		44,940
Loans and Leases Receivable, Allowance, Total	46,052	43,224	44,940
Loans, Individually Evaluated for Credit Loss	20,258		10,544
Loans, Collectively Evaluated for Credit Loss	3,245,187		3,163,805
Totals	3,265,445		3,174,349
1-4 Family Mortgage
Allowance for Credit Losses for Loans and Leases:
Beginning Balance	2,795	2,651	2,651
Provision for (Recovery of) Credit Losses on Loans and Leases	(210)	102
Recoveries of Loans		1
Total Ending Allowance Balance	2,585	2,754	2,795
Allowance for loan losses and the recorded investment
Allowance for Loan Losses and Loans, Collectively Evaluated for Credit Loss	2,585		2,795
Loans and Leases Receivable, Allowance, Total	2,585	2,754	2,795
Loans, Individually Evaluated for Credit Loss	1,039		708
Loans, Collectively Evaluated for Credit Loss	478,422		473,675
Totals	479,461		474,383
Multifamily
Allowance for Credit Losses for Loans and Leases:
Beginning Balance	23,120	22,217	22,217
Provision for (Recovery of) Credit Losses on Loans and Leases	807	13
Total Ending Allowance Balance	23,927	22,230	23,120
Allowance for loan losses and the recorded investment
Allowance for Loan Losses and Loans, Collectively Evaluated for Credit Loss	23,927		23,120
Loans and Leases Receivable, Allowance, Total	23,927	22,230	23,120
Loans, Individually Evaluated for Credit Loss	1,033
Loans, Collectively Evaluated for Credit Loss	1,533,714		1,425,610
Totals	1,534,747		1,425,610
CRE Owner Occupied
Allowance for Credit Losses for Loans and Leases:
Beginning Balance	1,290	1,184	1,184
Provision for (Recovery of) Credit Losses on Loans and Leases	(64)	51
Total Ending Allowance Balance	1,226	1,235	1,290
Allowance for loan losses and the recorded investment
Allowance for Loan Losses and Loans, Collectively Evaluated for Credit Loss	1,226		1,290
Loans and Leases Receivable, Allowance, Total	1,226	1,235	1,290
Loans, Individually Evaluated for Credit Loss	1,546		1,558
Loans, Collectively Evaluated for Credit Loss	194,534		189,690
Totals	196,080		191,248
CRE Non-owner Occupied
Allowance for Credit Losses for Loans and Leases:
Beginning Balance	17,735	16,225	16,225
Provision for (Recovery of) Credit Losses on Loans and Leases	579	780
Total Ending Allowance Balance	18,314	17,005	17,735
Allowance for loan losses and the recorded investment
Allowance for Loan Losses and Loans, Individually Evaluated for Credit Loss	1,737
Allowance for Loan Losses and Loans, Collectively Evaluated for Credit Loss	16,577		17,735
Loans and Leases Receivable, Allowance, Total	18,314	17,005	17,735
Loans, Individually Evaluated for Credit Loss	16,640		8,278
Loans, Collectively Evaluated for Credit Loss	1,038,517		1,074,830
Totals	1,055,157		1,083,108
Consumer and other
Allowance for Credit Losses for Loans and Leases:
Beginning Balance	142	105	105
Provision for (Recovery of) Credit Losses on Loans and Leases	4	7
Loans and Leases Charged-off	(12)	(2)
Recoveries of Loans	1	1
Total Ending Allowance Balance	135	111	142
Allowance for loan losses and the recorded investment
Allowance for Loan Losses and Loans, Individually Evaluated for Credit Loss			5
Allowance for Loan Losses and Loans, Collectively Evaluated for Credit Loss	135		137
Loans and Leases Receivable, Allowance, Total	135	$ 111	142
Loans, Individually Evaluated for Credit Loss			18
Loans, Collectively Evaluated for Credit Loss	14,361		12,978
Totals	$ 14,361		$ 12,996

No definition available.

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

- Definition

Amount excluding accrued interest, of allowance for credit loss on financing receivable. Excludes net investment in lease.

+ References

+ Details

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of allowance for credit loss on financing receivable evaluated on collective basis. Excludes financing receivable evaluated on individual basis.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 4
-Subparagraph (SAB Topic 6.L.5.a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480418/310-10-S99-4

Reference 2: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 11B
-Subparagraph (g)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481962/310-10-50-11B

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 30
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479391/326-20-30-2

+ Details

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of allowance for credit loss on financing receivable evaluated on individual basis. Excludes financing receivable evaluated on collective basis.

+ References

+ Details

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of increase in allowance for credit loss on financing receivable from recovery.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 11B
-Subparagraph (c)(4)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481962/310-10-50-11B

Reference 2: 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 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-13

+ Details

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

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

- Definition

Amount of writeoff of financing receivable, charged against allowance for credit loss.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 11B
-Subparagraph (c)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481962/310-10-50-11B

Reference 2: 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 3: 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 4: 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_FinancingReceivableAllowanceForCreditLossesWriteOffs
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of financing receivable collectively evaluated for credit loss. Excludes financing receivable individually evaluated for credit loss.

+ References

+ Details

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

- Definition

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

+ References

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

Amount of financing receivable individually evaluated for credit loss. Excludes financing receivable collectively evaluated for credit loss.

+ References

+ Details

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

- Definition

Amount of credit loss expense (reversal of expense) for financing receivable.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(11))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478524/942-220-S99-1

+ Details

Name:	us-gaap_ProvisionForLoanLossesExpensed
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

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

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=bwb_LeasePortfolioSegmentMember
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_RealEstatePortfolioSegmentMember
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: