Debt Instrument, Amortization Period

No definition available.

Name:	bfs_DebtInstrumentAmortizationPeriod
Namespace Prefix:	bfs_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of accumulated amortization of debt issuance costs.

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

+ References

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+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Face (par) amount of debt instrument at time of issuance.

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+ Details

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
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

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of the required periodic payments including both interest and principal payments.

+ References

+ Details

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

- Definition

Amount of payment greater than the preceding installment payments to be paid at final maturity date of debt.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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

- Definition

Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

+ References

+ Details

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

- Definition

Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The portion of the carrying amount of long-term borrowings outstanding as of the balance sheet date, including current maturities, which accrues interest at a set, unchanging rate.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The portion of the carrying amount of long-term borrowings outstanding as of the balance sheet date, including current maturities, which accrues interest at a rate subject to change from time to time.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
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Balance Type:	credit
Period Type:	instant

- Definition

Amount, before accumulated depreciation, of real estate investment by entity with substantial portion of business acquiring and holding investment real estate or interest in real estate. Excludes real estate not held as investment or interest.

+ References

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Carrying value as of the balance sheet date, including the current and noncurrent portions, of collateralized debt obligations (with maturities initially due after one year or beyond the operating cycle, if longer). Such obligations include mortgage loans, chattel loans, and any other borrowings secured by assets of the borrower.

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Namespace Prefix:	us-gaap_
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Period Type:	instant

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- Details

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- Details

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- Details

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Notes Payable, Revolving Credit Facility, Interest and Amortization of Deferred Debt Costs - Narrative (Details) - USD ($)		9 Months Ended
	Jan. 10, 2019	Sep. 30, 2019	Oct. 01, 2021	Oct. 01, 2020	Oct. 01, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Principal amount		$ 1,023,104,000				$ 1,000,000,000.0
Debt outstanding with fixed-rate		948,100,000				910,200,000
Debt outstanding with variable-rate		75,000,000.0				122,000,000.0
Outstanding line of credit		0				45,329,000
Carrying value of properties collateralizing mortgage notes		1,100,000,000				1,100,000,000
Final payment amount		756,805,000
Notes payable		846,525,000				880,271,000
Principal amount		1,014,728,000
Unamortized deferred debt costs		8,376,000				10,300,000
Debt issuance costs amortization		6,700,000				7,300,000
Unsecured Revolving Credit Facility
Debt Instrument [Line Items]
Outstanding line of credit						$ 47,000,000.0
Line of credit facility, remaining borrowing capacity		296,300,000
Letter of Credit
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity		185,000
New Facility \| Line of Credit
Debt Instrument [Line Items]
Outstanding line of credit		0
Line of credit facility, maximum borrowing capacity		400,000,000.0
Unamortized deferred debt costs		1,300,000
Debt issuance costs amortization		900,000
New Facility \| Term Loan \| Line of Credit
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity		$ 75,000,000.0
New Facility \| Term Loan \| LIBOR
Debt Instrument [Line Items]
Interest rate spread on LIBOR (percentage)		1.30%
New Facility \| Revolving Line \| Line of Credit
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity		$ 325,000,000.0
New Facility \| Revolving Line \| LIBOR
Debt Instrument [Line Items]
Interest rate spread on LIBOR (percentage)		1.35%
Park Van Ness Loan
Debt Instrument [Line Items]
Guarantor obligations, maximum exposure		$ 10,000,000.0
Notes payable		68,500,000
Broadlands Village Mortgage
Debt Instrument [Line Items]
Guarantor obligations, maximum exposure		3,900,000
Principal amount		31,400,000
Olde Forte Village \| 4.65% due January 2034
Debt Instrument [Line Items]
Debt instrument, term	15 years
Construction-to-permanent loan	$ 22,100,000
Interest rate, stated percentage	4.65%
Periodic payment	$ 124,700
Amortization period	25 years
Final payment amount	$ 12,100,000
Kentlands Square II Bank Loan \| Fixed Rate Mortgage Notes Payable
Debt Instrument [Line Items]
Guarantor obligations, maximum exposure		8,600,000
Principal amount		$ 34,300,000
Forecast \| Park Van Ness Loan
Debt Instrument [Line Items]
Guarantor obligations, maximum exposure			$ 0	$ 3,300,000	$ 6,700,000