Loans and Allowance for Credit Loses - Allowance for loan losses by segment (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended	12 Months Ended
Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025	Dec. 31, 2025
Allowance for Credit Losses for Loans and Leases:
Beginning Balance	$ 57,277	$ 53,766	$ 56,443	$ 52,277	$ 52,277
Provision for (Recovery of) Credit Losses for Loans and Leases	550	2,000	1,900	3,500
Loans and Leases Charged-off	(738)	(6)	(1,396)	(18)
Recoveries of Loans and Leases	329	5	471	6
Total Ending Allowance Balance	57,418	55,765	57,418	55,765	56,443
Allowance for loan losses and the recorded investment
Allowance for Loan Losses and Loans, Individually Evaluated for Credit Loss	5,283		5,283		3,812
Allowance for Loan Losses and Loans, Collectively Evaluated for Credit Loss	52,135		52,135		52,631
Allowance for Credit Loss Total	57,418	55,765	57,418	55,765	56,443
Loans, Individually Evaluated for Credit Loss	43,888		43,888		55,757
Loans, Collectively Evaluated for Credit Loss	4,382,501		4,382,501		4,253,760
Totals	4,426,389		4,426,389		4,309,517
Commercial
Allowance for Credit Losses for Loans and Leases:
Beginning Balance	6,395	5,847	5,982	5,630	5,630
Provision for (Recovery of) Credit Losses for Loans and Leases	(677)	87	237	304
Loans and Leases Charged-off			(639)
Recoveries of Loans and Leases	328	1	466	1
Total Ending Allowance Balance	6,046	5,935	6,046	5,935	5,982
Allowance for loan losses and the recorded investment
Allowance for Loan Losses and Loans, Individually Evaluated for Credit Loss	189		189		134
Allowance for Loan Losses and Loans, Collectively Evaluated for Credit Loss	5,857		5,857		5,848
Allowance for Credit Loss Total	6,046	5,935	6,046	5,935	5,982
Loans, Individually Evaluated for Credit Loss	10,430		10,430		10,527
Loans, Collectively Evaluated for Credit Loss	580,604		580,604		536,718
Totals	591,034		591,034		547,245
Leases
Allowance for Credit Losses for Loans and Leases:
Beginning Balance	305	365	352	368	368
Provision for (Recovery of) Credit Losses for Loans and Leases	(9)	16	(56)	13
Total Ending Allowance Balance	296	381	296	381	352
Allowance for loan losses and the recorded investment
Allowance for Loan Losses and Loans, Collectively Evaluated for Credit Loss	296		296		352
Allowance for Credit Loss Total	296	381	296	381	352
Loans, Collectively Evaluated for Credit Loss	41,802		41,802		43,407
Totals	41,802		41,802		43,407
Construction and Land Development
Allowance for Credit Losses for Loans and Leases:
Beginning Balance	1,696	1,075	1,687	866	866
Provision for (Recovery of) Credit Losses for Loans and Leases	(296)	29	(287)	238
Total Ending Allowance Balance	1,400	1,104	1,400	1,104	1,687
Allowance for loan losses and the recorded investment
Allowance for Loan Losses and Loans, Collectively Evaluated for Credit Loss	1,400		1,400		1,687
Allowance for Credit Loss Total	1,400	1,104	1,400	1,104	1,687
Loans, Individually Evaluated for Credit Loss	26		26		34
Loans, Collectively Evaluated for Credit Loss	186,222		186,222		216,129
Totals	186,248		186,248		216,163
1-4 Family Construction
Allowance for Credit Losses for Loans and Leases:
Beginning Balance	355	292	316	331	331
Provision for (Recovery of) Credit Losses for Loans and Leases	(42)	(14)	(3)	(53)
Total Ending Allowance Balance	313	278	313	278	316
Allowance for loan losses and the recorded investment
Allowance for Loan Losses and Loans, Collectively Evaluated for Credit Loss	313		313		316
Allowance for Credit Loss Total	313	278	313	278	316
Loans, Collectively Evaluated for Credit Loss	46,539		46,539		45,152
Totals	46,539		46,539		45,152
Real Estate Mortgage
Allowance for Credit Losses for Loans and Leases:
Beginning Balance	48,267	46,052	47,925	44,940	44,940
Provision for (Recovery of) Credit Losses for Loans and Leases	1,535	1,862	1,877	2,974
Loans and Leases Charged-off	(718)		(718)
Total Ending Allowance Balance	49,084	47,914	49,084	47,914	47,925
Allowance for loan losses and the recorded investment
Allowance for Loan Losses and Loans, Individually Evaluated for Credit Loss	5,014		5,014		3,678
Allowance for Loan Losses and Loans, Collectively Evaluated for Credit Loss	44,070		44,070		44,247
Allowance for Credit Loss Total	49,084	47,914	49,084	47,914	47,925
Loans, Individually Evaluated for Credit Loss	32,623		32,623		45,196
Loans, Collectively Evaluated for Credit Loss	3,503,247		3,503,247		3,393,142
Totals	3,535,870		3,535,870		3,438,338
1-4 Family Mortgage
Allowance for Credit Losses for Loans and Leases:
Beginning Balance	2,385	2,585	2,475	2,795	2,795
Provision for (Recovery of) Credit Losses for Loans and Leases	(100)	(172)	(190)	(382)
Loans and Leases Charged-off	(9)		(9)
Total Ending Allowance Balance	2,276	2,413	2,276	2,413	2,475
Allowance for loan losses and the recorded investment
Allowance for Loan Losses and Loans, Collectively Evaluated for Credit Loss	2,276		2,276		2,475
Allowance for Credit Loss Total	2,276	2,413	2,276	2,413	2,475
Loans, Individually Evaluated for Credit Loss	1,328		1,328		1,000
Loans, Collectively Evaluated for Credit Loss	483,960		483,960		495,142
Totals	485,288		485,288		496,142
Multifamily
Allowance for Credit Losses for Loans and Leases:
Beginning Balance	24,140	23,927	23,775	23,120	23,120
Provision for (Recovery of) Credit Losses for Loans and Leases	1,588	(6)	1,953	801
Loans and Leases Charged-off	(709)		(709)
Total Ending Allowance Balance	25,019	23,921	25,019	23,921	23,775
Allowance for loan losses and the recorded investment
Allowance for Loan Losses and Loans, Individually Evaluated for Credit Loss	995		995		789
Allowance for Loan Losses and Loans, Collectively Evaluated for Credit Loss	24,024		24,024		22,986
Allowance for Credit Loss Total	25,019	23,921	25,019	23,921	23,775
Loans, Individually Evaluated for Credit Loss	12,118		12,118		23,776
Loans, Collectively Evaluated for Credit Loss	1,678,448		1,678,448		1,563,562
Totals	1,690,566		1,690,566		1,587,338
CRE Owner Occupied
Allowance for Credit Losses for Loans and Leases:
Beginning Balance	1,065	1,226	1,080	1,290	1,290
Provision for (Recovery of) Credit Losses for Loans and Leases	(32)	(89)	(47)	(153)
Total Ending Allowance Balance	1,033	1,137	1,033	1,137	1,080
Allowance for loan losses and the recorded investment
Allowance for Loan Losses and Loans, Collectively Evaluated for Credit Loss	1,033		1,033		1,080
Allowance for Credit Loss Total	1,033	1,137	1,033	1,137	1,080
Loans, Individually Evaluated for Credit Loss	3,355		3,355		3,553
Loans, Collectively Evaluated for Credit Loss	187,798		187,798		186,201
Totals	191,153		191,153		189,754
CRE Non-owner Occupied
Allowance for Credit Losses for Loans and Leases:
Beginning Balance	20,677	18,314	20,595	17,735	17,735
Provision for (Recovery of) Credit Losses for Loans and Leases	79	2,129	161	2,708
Total Ending Allowance Balance	20,756	20,443	20,756	20,443	20,595
Allowance for loan losses and the recorded investment
Allowance for Loan Losses and Loans, Individually Evaluated for Credit Loss	4,019		4,019		2,889
Allowance for Loan Losses and Loans, Collectively Evaluated for Credit Loss	16,737		16,737		17,706
Allowance for Credit Loss Total	20,756	20,443	20,756	20,443	20,595
Loans, Individually Evaluated for Credit Loss	15,822		15,822		16,867
Loans, Collectively Evaluated for Credit Loss	1,153,041		1,153,041		1,148,237
Totals	1,168,863		1,168,863		1,165,104
Consumer and other
Allowance for Credit Losses for Loans and Leases:
Beginning Balance	259	135	181	142	142
Provision for (Recovery of) Credit Losses for Loans and Leases	39	20	132	24
Loans and Leases Charged-off	(20)	(6)	(39)	(18)
Recoveries of Loans and Leases	1	4	5	5
Total Ending Allowance Balance	279	153	279	153	181
Allowance for loan losses and the recorded investment
Allowance for Loan Losses and Loans, Individually Evaluated for Credit Loss	80		80
Allowance for Loan Losses and Loans, Collectively Evaluated for Credit Loss	199		199		181
Allowance for Credit Loss Total	279	$ 153	279	$ 153	181
Loans, Individually Evaluated for Credit Loss	809		809
Loans, Collectively Evaluated for Credit Loss	24,087		24,087		19,212
Totals	$ 24,896		$ 24,896		$ 19,212

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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477657/942-210-S45-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478478/942-210-S50-1

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(7)(2))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1

Reference 4: 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

+ 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://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 13
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-13

Reference 3: 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

+ 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://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 13
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-13

Reference 3: 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 4: 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_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/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

Reference 2: 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 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_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 220
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 22
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147476148/220-40-50-22

Reference 3: 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: