Name:	fhlbsf_FederalHomeLoanBankAdvancesWithPartialPrepaymentSymmetryOutstanding
Namespace Prefix:	fhlbsf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The amount of Federal Home Loan Bank advances with full prepayment symmetry outstanding as of the latest balance sheet date. Repayment of advances with full prepayment symmetry may result in a payment or receipt of a prepayment, depending upon circumstances, such as movements in interest rates.

No definition available.

Name:	fhlbsf_FederalHomeLoanBankAdvanceswithFullprepaymentSymmetryOutstanding
Namespace Prefix:	fhlbsf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Interest rate of advances made and reported by Federal Home Loan Bank (FHLBank).

No definition available.

Name:	us-gaap_FederalHomeLoanBankAdvancesInterestRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

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.

No definition available.

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

Maturity period on fixed rate advances made and reported by Federal Home Loan Bank (FHLBank), in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

No definition available.

Name:	us-gaap_FederalHomeLoanBankAdvancesMaturityPeriodFixedRate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Maturity period on variable rate advances made and reported by Federal Home Loan Bank (FHLBank), in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

No definition available.

Name:	us-gaap_FederalHomeLoanBankAdvancesMaturityPeriodVariableRate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Par amount of advances made and reported by Federal Home Loan Bank (FHLBank).

No definition available.

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

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