Allowance For Unfunded Commitments

No definition available.

Name:	hmst_AllowanceForUnfundedCommitments
Namespace Prefix:	hmst_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Number Of Portfolio Segments

+ References

No definition available.

+ Details

Name:	hmst_NumberOfPortfolioSegments
Namespace Prefix:	hmst_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of total loan portfolio.

+ References

No definition available.

+ Details

Name:	hmst_PercentageOfLoanPortfolio
Namespace Prefix:	hmst_
Data Type:	dtr-types1:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount, after allowance for credit loss, of accrued interest on financing receivable.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479344/326-20-45-5

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

+ Details

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

- Definition

Amortized cost excluding accrued interest, after 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

+ 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, of financing receivable with payment default in current period and modified within previous 12 months preceding payment default for debtor experiencing financial difficulty.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 44
-Subparagraph (a)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481962/310-10-50-44

+ Details

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

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

- Details

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

- Details

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

- Details

Name:	us-gaap_LoanRestructuringModificationAxis=us-gaap_PaymentDeferralMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LoanRestructuringModificationAxis=us-gaap_ExtendedMaturityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LoanRestructuringModificationAxis=us-gaap_ExtendedMaturityAndInterestRateReductionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LoanRestructuringModificationAxis=hmst_PaymentDeferralAndExtendedMaturityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LoanRestructuringModificationAxis=hmst_ContractualInterestRateReductionPaymentDeferralAndExtendedMaturityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementGeographicalAxis=stpr_CA
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=hmst_SingleAndMultifamilyResidentialMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementGeographicalAxis=stpr_WA
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_FederalHomeLoanBankAdvancesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PledgedStatusAxis=us-gaap_AssetPledgedAsCollateralWithoutRightMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_FederalReserveBankAdvancesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

LOANS AND CREDIT QUALITY - Narrative (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($) portfolioSegment	Sep. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)
Financing Receivable, Impaired [Line Items]
Number of portfolio segments \| portfolioSegment			2
Loans held for investment ("LHFI")	$ 7,400,501		$ 7,400,501		$ 7,384,820
Allowance for unfunded commitments	1,600		1,600		2,200
Accrued interest receivable	27,700		27,700		$ 26,900
Single family \| Consumer loans \| Significant Payment Delay
Financing Receivable, Impaired [Line Items]
Loan modifications with subsequent default	235	$ 0	235	$ 0
Single family \| Consumer loans \| Term Extension
Financing Receivable, Impaired [Line Items]
Loan modifications with subsequent default	0	0	0	0
Single family \| Consumer loans \| Interest Rate Reduction and Term Extension
Financing Receivable, Impaired [Line Items]
Loan modifications with subsequent default	0	0	0	0
Single family \| Consumer loans \| Significant Payment Delay and Term Extension
Financing Receivable, Impaired [Line Items]
Loan modifications with subsequent default	634	0	2,879	172
Single family \| Consumer loans \| Interest Rate Reduction, Significant Payment Delay and Term Extension
Financing Receivable, Impaired [Line Items]
Loan modifications with subsequent default	$ 70	$ 553	$ 1,162	$ 1,555
California \| Multifamily
Financing Receivable, Impaired [Line Items]
Percentage of loan portfolio					36.00%
California \| Single and Multifamily Residental
Financing Receivable, Impaired [Line Items]
Percentage of loan portfolio	36.00%		36.00%
Washington \| Single and Multifamily Residental
Financing Receivable, Impaired [Line Items]
Percentage of loan portfolio	11.00%		11.00%
Federal Home Loan Bank Advances \| Asset Pledged as Collateral without Right
Financing Receivable, Impaired [Line Items]
Loans held for investment ("LHFI")	$ 5,700,000		$ 5,700,000		$ 5,200,000
Federal Reserve Bank Advances \| Asset Pledged as Collateral without Right
Financing Receivable, Impaired [Line Items]
Loans held for investment ("LHFI")	$ 528,000		$ 528,000		$ 497,000