Loans - Recorded investment in past due loans by loan segment (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Aging of the recorded investment in past due loans by loan segment
Nonaccrual	$ 663	$ 722
Totals	3,380,082	2,819,472
Current
Aging of the recorded investment in past due loans by loan segment
Loans	3,379,381	2,818,701
30-89 Days Past Due
Aging of the recorded investment in past due loans by loan segment
Loans	38	49
Commercial
Aging of the recorded investment in past due loans by loan segment
Totals	412,448	360,169
Commercial \| Current
Aging of the recorded investment in past due loans by loan segment
Loans	412,448	360,169
Paycheck Protection Program (PPP), CARES Act
Aging of the recorded investment in past due loans by loan segment
Totals	1,192	26,162
Paycheck Protection Program (PPP), CARES Act \| Current
Aging of the recorded investment in past due loans by loan segment
Loans	1,155	26,162
Paycheck Protection Program (PPP), CARES Act \| 30-89 Days Past Due
Aging of the recorded investment in past due loans by loan segment
Loans	37
Construction and Land Development
Aging of the recorded investment in past due loans by loan segment
Nonaccrual	110	130
Totals	335,557	281,474
Construction and Land Development \| Current
Aging of the recorded investment in past due loans by loan segment
Loans	335,447	281,344
HELOC and 1-4 Family Junior Mortgage
Aging of the recorded investment in past due loans by loan segment
Totals	29,981	31,260
HELOC and 1-4 Family Junior Mortgage \| Current
Aging of the recorded investment in past due loans by loan segment
Loans	29,981	31,211
HELOC and 1-4 Family Junior Mortgage \| 30-89 Days Past Due
Aging of the recorded investment in past due loans by loan segment
Loans		49
1st REM - 1-4 Family
Aging of the recorded investment in past due loans by loan segment
Totals	51,924	48,713
1st REM - 1-4 Family \| Current
Aging of the recorded investment in past due loans by loan segment
Loans	51,924	48,713
LOCs and 2nd REM - Rentals
Aging of the recorded investment in past due loans by loan segment
Totals	25,174	21,641
LOCs and 2nd REM - Rentals \| Current
Aging of the recorded investment in past due loans by loan segment
Loans	25,174	21,641
1st REM - Rentals
Aging of the recorded investment in past due loans by loan segment
Totals	234,023	203,703
1st REM - Rentals \| Current
Aging of the recorded investment in past due loans by loan segment
Loans	234,023	203,703
Multifamily
Aging of the recorded investment in past due loans by loan segment
Totals	1,230,509	910,243
Multifamily \| Current
Aging of the recorded investment in past due loans by loan segment
Loans	1,230,509	910,243
CRE Owner Occupied
Aging of the recorded investment in past due loans by loan segment
Nonaccrual	553	592
Totals	151,088	111,096
CRE Owner Occupied \| Current
Aging of the recorded investment in past due loans by loan segment
Loans	150,535	110,504
CRE Non-owner Occupied
Aging of the recorded investment in past due loans by loan segment
Totals	900,691	818,569
CRE Non-owner Occupied \| Current
Aging of the recorded investment in past due loans by loan segment
Loans	900,691	818,569
Consumer and other
Aging of the recorded investment in past due loans by loan segment
Totals	7,495	6,442
Consumer and other \| Current
Aging of the recorded investment in past due loans by loan segment
Loans	7,494	$ 6,442
Consumer and other \| 30-89 Days Past Due
Aging of the recorded investment in past due loans by loan segment
Loans	$ 1

Amortized cost of financing receivable on nonaccrual status. Excludes net investment in lease.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=123577603&loc=d3e5111-111524

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 16
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=124255953&loc=SL82919258-210447

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher SEC
-Name Regulation S-K (SK)
-Number 229
-Section 1405
-Paragraph (a)
-Subparagraph (3)

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher SEC
-Name Regulation S-K (SK)
-Number 229
-Section 1405
-Paragraph (a)
-Subparagraph (2)

+ Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
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

No definition available.

+ Details

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

- Definition

Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI https://asc.fasb.org/extlink&oid=124259787&loc=d3e4428-111522

+ Details

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

- Definition

Amortized cost, before allowance for credit loss, of financing receivable. Excludes financing receivable covered under loss sharing agreement and net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7A
-URI https://asc.fasb.org/extlink&oid=123577603&loc=SL6953401-111524

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 55
-Paragraph 79
-URI https://asc.fasb.org/extlink&oid=124267575&loc=SL82922352-210448

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(3)(b))
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 14
-URI https://asc.fasb.org/extlink&oid=124255953&loc=SL82919253-210447

Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 45
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=124255206&loc=SL82895884-210446

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 5
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=124255953&loc=SL82919230-210447

Reference 7: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 55
-Paragraph 80
-URI https://asc.fasb.org/extlink&oid=124267575&loc=SL82922355-210448

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher SEC
-Name Regulation S-K (SK)
-Number 229
-Section 1405
-Paragraph (a)
-Subparagraph (1)

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher SEC
-Name Regulation S-K (SK)
-Number 229
-Section 1405
-Paragraph (a)
-Subparagraph (2)

Reference 10: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher SEC
-Name Regulation S-K (SK)
-Number 229
-Section 1404
-Paragraph (a)

+ Details

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

- 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_PaycheckProtectionProgramPortfolioSegmentMember
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_HomeEquityLineOfCreditAndOneToFourFamilyJuniorMortgageMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=bwb_RealEstateMortgageOneRentalsMember
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: