No definition available.

Name:	us-gaap_AccountsNotesAndLoansReceivableClassifiedAbstract
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

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

+ References

+ Details

Name:	us-gaap_FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss
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

Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 825
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 10
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482907/825-10-50-10

+ Details

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

- Details

Name:	us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsRecurringMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_ResidentialMortgageMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=hmst_HomeEquityLineOfCreditAdjustedForCreditAnalysisMember
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_EquitySecuritiesByIndustryAxis=us-gaap_RealEstateSectorMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_EquitySecuritiesByIndustryAxis=us-gaap_CommercialAndIndustrialSectorMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=hmst_NonOwnerOccupiedCommercialRealEstateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=hmst_MultifamilyResidentialMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_ConstructionLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=hmst_OwnerOccupiedCommercialRealEstateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_CommercialLoanMember
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:

LOANS AND CREDIT QUALITY - Loans Held for Investment (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Jun. 30, 2024	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Dec. 31, 2022
Loans held for investment
Loans held for investment	$ 7,333,254		$ 7,422,904
Allowance for credit losses	(38,651)	$ (39,741)	(40,500)	$ (40,000)	$ (41,500)	$ (41,500)
Loans held for investment less allowance for credit losses	7,294,603		7,382,404
Recurring
Loans held for investment
Single family LHFI	1,329		1,280
Recurring \| Level 3
Loans held for investment
Single family LHFI	1,329		1,280
Single family
Loans held for investment
Allowance for credit losses	(3,804)			(5,783)
Home equity and other
Loans held for investment
Allowance for credit losses	(3,251)			(3,962)
Commercial and industrial loans
Loans held for investment
Loans held for investment	5,788,635		5,898,324
Commercial and industrial loans \| Real Estate Sector
Loans held for investment
Loans held for investment	5,077,498		5,147,990
Allowance for credit losses	(26,485)	(26,598)	(27,912)	(25,552)	(26,160)	(27,859)
Commercial and industrial loans \| Commercial and Industrial Sector
Loans held for investment
Loans held for investment	711,137		750,334
Allowance for credit losses	(5,111)	(6,326)	(3,849)	(4,703)	(4,767)	(4,277)
Commercial and industrial loans \| Non-owner occupied CRE
Loans held for investment
Loans held for investment	590,956		641,885
Allowance for credit losses	(1,812)	(1,777)	(2,610)	(2,365)	(2,242)	(2,102)
Commercial and industrial loans \| Multifamily
Loans held for investment
Loans held for investment	3,950,941		3,940,189
Allowance for credit losses	(15,760)	(17,070)	(13,093)	(10,706)	(9,695)	(10,974)
Commercial and industrial loans \| Construction/land development
Loans held for investment
Loans held for investment	535,601		565,916
Commercial and industrial loans \| Owner occupied CRE
Loans held for investment
Loans held for investment	365,138		391,285
Allowance for credit losses	(639)	(731)	(899)	(1,102)	(930)	(1,030)
Commercial and industrial loans \| Commercial business
Loans held for investment
Loans held for investment	345,999		359,049
Allowance for credit losses	(4,472)	(5,595)	(2,950)	(3,601)	(3,837)	(3,247)
Consumer loans
Loans held for investment
Loans held for investment	1,544,619		1,524,580
Allowance for credit losses	(7,055)	(6,817)	(8,739)	(9,745)	(10,573)	(9,364)
Consumer loans \| Single family
Loans held for investment
Loans held for investment	1,137,981		1,140,279
Allowance for credit losses	(3,804)	(3,844)	(5,287)	(5,783)	(6,617)	(5,610)
Consumer loans \| Home equity and other
Loans held for investment
Loans held for investment	406,638		384,301
Allowance for credit losses	$ (3,251)	$ (2,973)	$ (3,452)	$ (3,962)	$ (3,956)	$ (3,754)