Saul Centers (BFS) 10-K 27 Feb 20 2019 FY Annual report Financial data

Cover Page

Cover Page - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2019	Feb. 20, 2020	Jun. 30, 2019
Document Information [Line Items]
Document type	10-K
Document Annual Report	true
Document period end date	Dec. 31, 2019
Document Transition Report	false
Entity File Number	1-12254
Entity registrant name	SAUL CENTERS INC.
Entity Incorporation, State or Country Code	MD
Entity Tax Identification Number	52-1833074
Entity Address, Address Line One	7501 Wisconsin Avenue
Entity Address, Address Line Two	Suite 1500E
Entity Address, City or Town	Bethesda
Entity Address, State or Province	MD
Entity Address, Postal Zip Code	20814-6522
City Area Code	301
Local Phone Number	986-6200
Entity well-known seasoned issuer	Yes
Entity voluntary filers	No
Entity current reporting status	Yes
Entity Interactive Data Current	Yes
Entity filer category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity common stock, shares outstanding		23.2
Entity public float			$ 723.3
Documents Incorporated by Reference	Registrant incorporates by reference into Part III (Items 10, 11, 12, 13 and 14) of this Annual Report on Form 10-K portions of registrant’s definitive Proxy Statement for the 2020 Annual Meeting of Stockholders to be filed with the Securities Exchange Commission pursuant to Regulation 14A. The definitive Proxy Statement will be filed with the Commission not later than 120 days after the end of the fiscal year covered by this Annual Report on Form 10-K.
Amendment flag	false
Document fiscal year focus	2019
Document fiscal period focus	FY
Entity central index key	0000907254
Current fiscal year end date	--12-31
Common Stock, $0.01 Par Value
Document Information [Line Items]
Title of 12(b) Security	Common Stock, $0.01 Par Value
Security Exchange Name	NYSE
Trading symbol	BFS
6.125% Series D Preferred Stock, $0.01 Par Value
Document Information [Line Items]
Title of 12(b) Security	6.125% Series D Preferred Stock, $0.01 Par Value
Security Exchange Name	NYSE
Trading symbol	BFS/PRD
6.000% Series E Preferred Stock, $0.01 Par Value
Document Information [Line Items]
Title of 12(b) Security	6.000% Series E Preferred Stock, $0.01 Par Value
Security Exchange Name	NYSE
Trading symbol	BFS/PRE

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Real estate investments
Land	$ 453,322	$ 488,918
Buildings and equipment	1,292,631	1,273,275
Construction in progress	335,644	185,972
Total Purchase Price	2,081,597	1,948,165
Accumulated depreciation	(563,474)	(525,518)
Book Value	1,518,123	1,422,647
Cash and cash equivalents	13,905	14,578
Accounts receivable and accrued income, net	52,311	53,876
Deferred leasing costs, net	24,083	28,083
Prepaid expenses, net	5,363	5,175
Other assets	4,555	3,130
Total assets	1,618,340	1,527,489
Liabilities
Mortgage notes payable	821,503	880,271
Term loan facility payable	74,691	74,591
Revolving credit facility payable	86,371	45,329
Construction loan payable	108,623	21,655
Dividends and distributions payable	19,291	19,153
Accounts payable, accrued expenses and other liabilities	35,199	32,419
Deferred income	29,306	28,851
Total liabilities	1,174,984	1,102,269
Equity
Common stock, $0.01 par value, 40,000,000 shares authorized, 23,231,240 and 22,739,207 shares issued and outstanding, respectively	232	227
Additional paid-in capital	410,926	384,533
Distributions in excess of accumulated earnings	(221,177)	(208,593)
Accumulated other comprehensive loss	0	(255)
Total Saul Centers, Inc. equity	374,981	355,912
Noncontrolling interests	68,375	69,308
Total equity	443,356	425,220
Total liabilities and equity	1,618,340	1,527,489
Series C Cumulative Preferred Stock
Equity
Preferred stock, 1,000,000 shares authorized, Series C Cumulative Redeemable, 0 and 42,000 shares issued and outstanding respectively, Series D Cumulative Redeemable, 30,000 shares issued and outstanding, Series E Cumulative Redeemable, 44,000 and 0 shares issued and outstanding respectively	0	105,000
Series D Cumulative Redeemable Preferred Stock
Equity
Preferred stock, 1,000,000 shares authorized, Series C Cumulative Redeemable, 0 and 42,000 shares issued and outstanding respectively, Series D Cumulative Redeemable, 30,000 shares issued and outstanding, Series E Cumulative Redeemable, 44,000 and 0 shares issued and outstanding respectively	75,000	75,000
Series E Cumulative Redeemable Preferred Stock
Equity
Preferred stock, 1,000,000 shares authorized, Series C Cumulative Redeemable, 0 and 42,000 shares issued and outstanding respectively, Series D Cumulative Redeemable, 30,000 shares issued and outstanding, Series E Cumulative Redeemable, 44,000 and 0 shares issued and outstanding respectively	$ 110,000	$ 0

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2019	Dec. 31, 2018
Preferred stock, shares authorized (in shares)	1,000,000	1,000,000
Common stock, par value (in usd per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	40,000,000	40,000,000
Common stock, shares issued (in shares)	23,231,240	22,739,207
Common stock, shares outstanding (in shares)	23,231,240	22,739,207
Series C Cumulative Preferred Stock
Cumulative redeemable preferred stock, shares issued (in shares)	0	42,000
Cumulative redeemable preferred stock, shares outstanding (in shares)	0	42,000
Series D Cumulative Redeemable Preferred Stock
Cumulative redeemable preferred stock, shares issued (in shares)	30,000	30,000
Cumulative redeemable preferred stock, shares outstanding (in shares)	30,000	30,000
Series E Cumulative Redeemable Preferred Stock
Cumulative redeemable preferred stock, shares issued (in shares)	44,000	0
Cumulative redeemable preferred stock, shares outstanding (in shares)	44,000	0

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenue
Rental revenue	$ 223,352	$ 221,734	$ 218,185
Other	8,173	5,485	8,114
Total revenue	231,525	227,219	226,299
Expenses
Property operating expenses	29,946	28,202	27,689
Real estate taxes	27,987	27,376	26,997
Interest expense, net and amortization of deferred debt costs	41,834	44,768	47,145
Depreciation and amortization of deferred leasing costs	46,333	45,861	45,694
General and administrative	20,793	18,459	18,176
Total expenses	166,893	164,666	165,701
Change in fair value of derivatives	(436)	(3)	70
Gains on sale of property	0	509	0
Net income (loss)	64,196	63,059	60,668
Income attributable to noncontrolling interests	(12,473)	(12,505)	(12,411)
Net income attributable to Saul Centers, Inc.	51,723	50,554	48,257
Preferred stock dividends	(12,235)	(12,262)	(12,375)
Extinguishment of issuance costs upon redemption of preferred shares	(3,235)	(2,328)	0
Net income available to common stockholders	$ 36,253	$ 35,964	$ 35,882
Per share net income available to common stockholders
Basic (in usd per share)	$ 1.58	$ 1.61	$ 1.64
Diluted (in usd per share)	$ 1.57	$ 1.60	$ 1.63

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 64,196	$ 63,059	$ 60,668
Other comprehensive income
Unrealized gain on cash flow hedge	93
Unrealized gain on cash flow hedge		594	812
Total comprehensive income	64,289	63,653	61,480
Comprehensive income attributable to noncontrolling interests	(12,561)	(12,658)	(12,620)
Total comprehensive income attributable to Saul Centers, Inc.	51,728	50,995	48,860
Preferred stock dividends	(12,235)	(12,262)	(12,375)
Extinguishment of issuance costs upon redemption of preferred shares	(3,235)	(2,328)	0
Total comprehensive income available to common stockholders	$ 36,258	$ 36,405	$ 36,485

Consolidated Statements of Equi

Consolidated Statements of Equity - USD ($) $ in Thousands	Total	Dividend paid	Dividend declared	Series C Cumulative Preferred Stock	Series C Cumulative Preferred StockDividend paid	Series C Cumulative Preferred StockDividend declared	Series D Cumulative Redeemable Preferred Stock	Series D Cumulative Redeemable Preferred StockDividend paid	Series D Cumulative Redeemable Preferred StockDividend declared	Series E Cumulative Redeemable Preferred Stock	Series E Cumulative Redeemable Preferred StockDividend paid	Preferred Stock	Preferred StockSeries C Cumulative Preferred Stock	Preferred StockSeries D Cumulative Redeemable Preferred Stock	Preferred StockSeries E Cumulative Redeemable Preferred Stock	Common Stock	Additional Paid-in Capital	Additional Paid-in CapitalSeries C Cumulative Preferred Stock	Additional Paid-in CapitalSeries D Cumulative Redeemable Preferred Stock	Additional Paid-in CapitalSeries E Cumulative Redeemable Preferred Stock	Distributions in Excess of Accumulated Earnings	Distributions in Excess of Accumulated EarningsDividend paid	Distributions in Excess of Accumulated EarningsDividend declared	Distributions in Excess of Accumulated EarningsSeries C Cumulative Preferred Stock	Distributions in Excess of Accumulated EarningsSeries C Cumulative Preferred StockDividend paid	Distributions in Excess of Accumulated EarningsSeries C Cumulative Preferred StockDividend declared	Distributions in Excess of Accumulated EarningsSeries D Cumulative Redeemable Preferred StockDividend paid	Distributions in Excess of Accumulated EarningsSeries D Cumulative Redeemable Preferred StockDividend declared	Distributions in Excess of Accumulated EarningsSeries E Cumulative Redeemable Preferred StockDividend paid	Accumulated Other Comprehensive (Loss)	Total Saul Centers, Inc.	Total Saul Centers, Inc.Dividend paid	Total Saul Centers, Inc.Dividend declared	Total Saul Centers, Inc.Series C Cumulative Preferred Stock	Total Saul Centers, Inc.Series C Cumulative Preferred StockDividend paid	Total Saul Centers, Inc.Series C Cumulative Preferred StockDividend declared	Total Saul Centers, Inc.Series D Cumulative Redeemable Preferred Stock	Total Saul Centers, Inc.Series D Cumulative Redeemable Preferred StockDividend paid	Total Saul Centers, Inc.Series D Cumulative Redeemable Preferred StockDividend declared	Total Saul Centers, Inc.Series E Cumulative Redeemable Preferred Stock	Noncontrolling Interests	Noncontrolling InterestsDividend paid	Noncontrolling InterestsDividend declared
Beginning balance at Dec. 31, 2016	$ 373,249											$ 180,000				$ 217	$ 328,171				$ (188,584)									$ (1,299)	$ 318,505										$ 54,744
Issuance of common stock:
Shares issued pursuant to dividend reinvestment plan	15,750															2	15,748														15,750
Shares issued due to exercise of employee stock options and issuance of directors' deferred stock	8,673															2	8,671														8,673
Issuance of partnership units	6,735																																								6,735
Net income	60,668																				48,257										48,257										12,411
Change in unrealized loss on cash flow hedge	812																													603	603										209
Preferred stock distributions:
Preferred stock distributions					$ (9,282)	$ (3,093)																			$ (9,282)	$ (3,093)									$ (9,282)	$ (3,093)
Common stock distributions		$ (44,969)																				$ (33,490)										$ (33,490)										$ (11,479)
Distributions payable common stock and distributions payable partnership units			$ (15,440)																				$ (11,518)										$ (11,518)										$ (3,922)
Ending balance at Dec. 31, 2017	393,103											180,000				221	352,590				(197,710)									(696)	334,405										58,698
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of cumulative preferred stock							$ 72,367							$ 75,000					$ (2,633)																		$ 72,367
Redemption of Series of Series C Cumulative preferred stock				$ (75,017)									$ (75,000)					$ 2,311						$ (2,328)										$ (75,017)
Issuance of common stock:
Shares issued pursuant to dividend reinvestment plan	28,823															6	28,817														28,823
Shares issued due to exercise of employee stock options and issuance of directors' deferred stock	3,448																3,448														3,448
Issuance of partnership units	14,159																																								14,159
Net income	63,059																				50,554										50,554										12,505
Change in unrealized loss on cash flow hedge	594																													441	441										153
Preferred stock distributions:
Preferred stock distributions					(6,145)	$ (1,805)		$ (3,164)	$ (1,148)																(6,145)	$ (1,805)	$ (3,164)	$ (1,148)							(6,145)	$ (1,805)		$ (3,164)	$ (1,148)
Common stock distributions		(46,900)																				(34,841)										(34,841)										(12,059)
Distributions payable common stock and distributions payable partnership units			(16,154)																				(12,006)										(12,006)										(4,148)
Ending balance at Dec. 31, 2018	425,220											180,000				227	384,533				(208,593)									(255)	355,912										69,308
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of cumulative preferred stock										$ 106,265					$ 110,000					$ (3,735)																				$ 106,265
Redemption of Series of Series C Cumulative preferred stock				$ 105,000									$ 105,000					$ (3,235)						$ (3,235)										$ 105,000
Issuance of common stock:
Shares issued pursuant to dividend reinvestment plan	22,498															4	22,494														22,498
Shares issued due to exercise of employee stock options and issuance of directors' deferred stock	4,400															1	4,399														4,400
Issuance of partnership units	3,180																																								3,180
Net income	64,196																				51,723										51,723										12,473
Change in unrealized loss on cash flow hedge	343																													255	255										88
Preferred stock distributions:
Preferred stock distributions			(1,650)		$ (5,736)			$ (3,444)	$ (1,148)		$ (257)												(1,650)		$ (5,736)		$ (3,444)	$ (1,148)	$ (257)				(1,650)		$ (5,736)			$ (3,444)	$ (1,148)
Common stock distributions		$ (49,056)																				$ (36,562)										$ (36,562)										$ (12,494)
Distributions payable common stock and distributions payable partnership units			$ (16,455)																				$ (12,275)										$ (12,275)										$ (4,180)
Ending balance at Dec. 31, 2019	$ 443,356											$ 185,000				$ 232	$ 410,926				$ (221,177)									$ 0	$ 374,981										$ 68,375

Consolidated Statements of Eq_2

Consolidated Statements of Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Shares issued pursuant to dividend reinvestment plan (in shares)	430,462,000	572,928	266,011
Shares due to exercise of employee stock options and issuance of directors' deferred stock (in shares)	61,571	43,150	152,758
Issuance of partnership units pursuant to dividend reinvestment plan (in shares)	60,936,000	107,433	111,351
Issuance of partnership units (in shares)	60,936	284,113
Series C Cumulative Preferred Stock
Redemption of Series C Cumulative preferred stock (in shares)	42,000	30,000
Series D Cumulative Redeemable Preferred Stock
Issuance of Series D Cumulative preferred stock (in shares)		30,000
Series E Cumulative Redeemable Preferred Stock
Issuance of Series D Cumulative preferred stock (in shares)	44,000
Dividend declared
Distributions payable common stock and partnership units (in usd per share)	$ 0.53	$ 0.53	$ 0.52
Dividend declared | Series C Cumulative Preferred Stock
Distributions payable on preferred stock (in usd per share)		42.97	$ 42.97
Dividend declared | Series D Cumulative Redeemable Preferred Stock
Distributions payable on preferred stock (in usd per share)	38.28	$ 38.28
Dividend declared | Series E Cumulative Redeemable Preferred Stock
Distributions payable on preferred stock (in usd per share)	$ 37.50

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net income		$ 64,196	$ 63,059	$ 60,668
Adjustments to reconcile net income to net cash provided by operating activities:
Change in fair value of derivatives		436	3	(70)
Gain on sale of property		0	(509)	0
Depreciation and amortization of deferred leasing costs		46,333	45,861	45,694
Amortization of deferred debt costs		1,518	1,610	1,392
Non cash compensation costs of stock grants and options		1,859	1,766	1,672
Provision for credit losses		1,226	685	906
(Increase) decrease in accounts receivable and accrued income		339	(336)	(1,643)
Additions to deferred leasing costs		(1,843)	(6,034)	(4,615)
(Increase) decrease in prepaid expenses		(188)	73	(294)
Decrease in other assets		894	3,681	1,374
Increase in accounts payable, accrued expenses and other liabilities		158	225	1,125
Increase (decrease) in deferred income		455	255	(2,759)
Net cash provided by operating activities		115,383	110,339	103,450
Cash flows from investing activities:
Acquisitions of real estate investments	[1]	0	(40,836)	(79,499)
Additions to real estate investments		(21,891)	(12,883)	(17,653)
Additions to development and redevelopment projects		(113,772)	(76,257)	(22,842)
Proceeds from sale of properties	[2]	0	1,326	6,688
Net cash used in investing activities		(135,663)	(128,650)	(113,306)
Cash flows from financing activities:
Proceeds from mortgage notes payable		50,600	54,900	100,000
Repayments on mortgage notes payable		(109,235)	(72,572)	(55,679)
Proceeds from term loan facility		0	75,000	0
Proceeds from revolving credit facility		152,500	102,000	63,000
Repayments on revolving credit facility		(112,000)	(116,000)	(51,000)
Proceeds from construction loans payable		86,868	23,332	1,437
Additions to deferred debt costs		(1,010)	(3,233)	(2,583)
Proceeds from the issuance of:
Common stock		25,039	30,503	22,751
Partnership units	[1]	3,180	5,383	6,735
Preferred stock redemption costs		0	(12)	0
Distributions to:
Distributions to preferred stockholders		(12,390)	(12,402)	(12,375)
Common stockholders		(48,568)	(46,306)	(44,576)
Noncontrolling interests		(16,642)	(15,981)	(15,268)
Net cash provided by financing activities		19,607	21,981	12,442
Net increase (decrease) in cash and cash equivalents		(673)	3,670	2,586
Cash and cash equivalents, beginning of year		14,578	10,908	8,322
Cash and cash equivalents, end of year		13,905	14,578	10,908
Supplemental disclosure of cash flow information:
Cash paid for interest		40,434	43,561	45,713
Increase (decrease) in accrued real estate investments and development costs		303	9,663	2,097
Series C Cumulative Preferred Stock
Proceeds from the issuance of:
Series C preferred stock redemption		(105,000)	(75,000)	0
Distributions to:
Distributions to preferred stockholders		(7,541)	(9,238)	(12,375)
Series D Cumulative Redeemable Preferred Stock
Proceeds from the issuance of:
Preferred stock		0	72,369	0
Distributions to:
Distributions to preferred stockholders		(4,592)	(3,164)	0
Series E Cumulative Redeemable Preferred Stock
Proceeds from the issuance of:
Preferred stock		106,265	0	0
Distributions to:
Distributions to preferred stockholders		$ (257)	0	$ 0
Ashbrook Marketplace
Supplemental disclosure of cash flow information:
Limited partnership units issued			8,776
Great Eastern Shopping Center
Supplemental disclosure of cash flow information:
Seller financing			1,275
Interest income			$ 51
[1]	The 2018 acquisition of real estate and proceeds from the issuance of partnership units each excludes $8,776 in connection with the acquisition of Ashbrook Marketplace in exchange for limited partnership units.
[2]	Proceeds from sale of property in 2017 excludes $1,275 of seller financing in connection with the sale of the Company's Great Eastern property, which were received in 2018 plus accrued interest of $51 .

Organization, Basis of Presenta

Organization, Basis of Presentation	12 Months Ended
	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization, Basis of Presentation	ORGANIZATION, BASIS OF PRESENTATION Saul Centers, Inc. (“Saul Centers”) was incorporated under the Maryland General Corporation Law on June 10, 1993. Saul Centers operates as a real estate investment trust (a “REIT”) under the Internal Revenue Code of 1986, as amended (the “Code”). The Company is required to annually distribute at least 90% of its REIT taxable income (excluding net capital gains) to its stockholders and meet certain organizational and other requirements. Saul Centers has made and intends to continue to make regular quarterly distributions to its stockholders. Saul Centers, together with its wholly owned subsidiaries and the limited partnerships of which Saul Centers or one of its subsidiaries is the sole general partner, are referred to collectively as the “Company.” B. Francis Saul II serves as Chairman of the Board of Directors, Chief Executive Officer and President of Saul Centers. Saul Centers was formed to continue and expand the shopping center business previously owned and conducted by the B. F. Saul Real Estate Investment Trust (the "Saul Trust"), the B. F. Saul Company and certain other affiliated entities, each of which is controlled by B. Francis Saul II and his family members (collectively, the “Saul Organization”). On August 26, 1993, members of the Saul Organization transferred to Saul Holdings Limited Partnership, a newly formed Maryland limited partnership (the “Operating Partnership”), and two newly formed subsidiary limited partnerships (the “Subsidiary Partnerships,” and collectively with the Operating Partnership, the “Partnerships”), Shopping Centers and Mixed-Used Properties, and the management functions related to the transferred properties. Since its formation, the Company has developed and purchased additional properties. The Company, which conducts all of its activities through its subsidiaries, the Operating Partnership and Subsidiary Partnerships, engages in the ownership, operation, management, leasing, acquisition, renovation, expansion, development and financing of community and neighborhood shopping centers and mixed-used properties, primarily in the Washington, DC/Baltimore metropolitan area. Because the properties are located primarily in the Washington, DC/Baltimore metropolitan area, a disproportionate economic downturn in the local economy would have a greater negative impact on our overall financial performance than on the overall financial performance of a company with a portfolio that is more geographically diverse. A majority of the Shopping Centers are anchored by several major tenants. As of December 31, 2019 , 33 of the Shopping Centers were anchored by a grocery store and offer primarily day-to-day necessities and services. One retail tenant, Giant Food ( 4.7% ), a tenant at ten Shopping Centers, individually accounted for 2.5% or more of the Company’s total revenue for the year ended December 31, 2019 . As of December 31, 2019 , the Current Portfolio Properties consisted of 50 Shopping Centers, six Mixed-Use Properties, and four (non-operating) development properties. The accompanying consolidated financial statements of the Company include the accounts of Saul Centers and its subsidiaries, including the Operating Partnership and Subsidiary Partnerships, which are majority owned by Saul Centers. Substantially all assets and liabilities of the Company as of December 31, 2019 and December 31, 2018 , are comprised of the assets and liabilities of the Operating Partnership. The debt arrangements which are subject to recourse are described in Note 5. All significant intercompany balances and transactions have been eliminated in consolidation. The Operating Partnership is a variable interest entity ("VIE") of the Company because the limited partners do not have substantive kick-out or participating rights. The Company is the primary beneficiary of the Operating Partnership because it has the power to direct the activities of the Operating Partnership and the rights to absorb 74.6% of the net income of the Operating Partnership. Because the Operating Partnership was already consolidated into the financial statements of the Company, the identification of it as a VIE has no impact on the consolidated financial statements of the Company.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make certain estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expenses during the reporting period. The most significant estimates and assumptions relate to impairment of real estate properties. Actual results could differ from those estimates. Real Estate Investment Properties Real estate investment properties are stated at historic cost less depreciation. Although the Company intends to own its real estate investment properties over a long term, from time to time it will evaluate its market position, market conditions, and other factors and may elect to sell properties that do not conform to the Company’s investment profile. Management believes that the Company’s real estate assets have generally appreciated in value since their acquisition or development and, accordingly, the aggregate current value exceeds their aggregate net book value and also exceeds the value of the Company’s liabilities as reported in the financial statements. Because the financial statements are prepared in conformity with GAAP, they do not report the current value of the Company’s real estate investment properties. If there is an event or change in circumstance that indicates a potential impairment in the value of a real estate investment property, the Company prepares an analysis to determine whether the carrying value of the real estate investment property exceeds its estimated fair value. The Company considers both quantitative and qualitative factors including recurring operating losses, significant decreases in occupancy, and significant adverse changes in legal factors and business climate. If impairment indicators are present, the Company compares the projected cash flows of the property over its remaining useful life, on an undiscounted basis, to the carrying value of that property. The Company assesses its undiscounted projected cash flows based upon estimated capitalization rates, historic operating results and market conditions that may affect the property. If the carrying value is greater than the undiscounted projected cash flows, the Company would recognize an impairment loss equivalent to an amount required to adjust the carrying amount to its then estimated fair value. The fair value of any property is sensitive to the actual results of any of the aforementioned estimated factors, either individually or taken as a whole. Should the actual results differ from management’s projections, the valuation could be negatively or positively affected. The Company did not recognize an impairment loss on any of its real estate in 2019 , 2018 , or 2017 . Depreciation is calculated using the straight-line method and estimated useful lives of generally between 35 and 50 years for base buildings, or a shorter period if management determines that the building has a shorter useful life, and up to 20 years for certain other improvements that extend the useful lives. Leasehold improvements expenditures are capitalized when certain criteria are met, including when the Company supervises construction and will own the improvements. Tenant improvements are amortized, over the shorter of the lives of the related leases or the useful life of the improvement, using the straight-line method. Depreciation expense, which is included in Depreciation and amortization of deferred leasing costs in the Consolidated Statements of Operations, for the years ended December 31, 2019 , 2018 , and 2017 , was $40.5 million , $39.8 million , and $40.2 million , respectively. Repairs and maintenance expense totaled $12.5 million , $11.9 million , and $11.6 million for 2019 , 2018 , and 2017 , respectively, and is included in property operating expenses in the accompanying consolidated financial statements. Assets Held for Sale The Company considers properties to be assets held for sale when all of the following criteria are met: • management commits to a plan to sell a property; • it is unlikely that the disposal plan will be significantly modified or discontinued; • the property is available for immediate sale in its present condition; • actions required to complete the sale of the property have been initiated; • sale of the property is probable and the Company expects the completed sale will occur within one year; and • the property is actively being marketed for sale at a price that is reasonable given its current market value. The Company must make a determination as to the point in time that it is probable that a sale will be consummated, which generally occurs when an executed sales contract has no contingencies and the prospective buyer has significant funds at risk to ensure performance. Upon designation as an asset held for sale, the Company records the carrying value of each property at the lower of its carrying value or its estimated fair value, less estimated costs to sell, and ceases depreciation. As of December 31, 2019 and 2018 , the Company had no assets designated as held for sale. Revenue Recognition Rental and interest income are accrued as earned. Recognition of rental income commences when control of the space has been given to the tenant. When rental payments due under leases vary from a straight-line basis because of free rent periods or stepped increases, income is recognized on a straight-line basis. Expense recoveries represent a portion of property operating expenses billed to the tenants, including common area maintenance, real estate taxes and other recoverable costs. Expense recoveries are recognized in the period in which the expenses are incurred. Rental income based on a tenant’s revenue (“percentage rent”) is accrued when a tenant reports sales that exceed a specified breakpoint, pursuant to the terms of their respective leases. Accounts Receivable, Accrued Income, and Allowance for Doubtful Accounts Accounts receivable primarily represent amounts currently due from tenants in accordance with the terms of their respective leases. Lease related receivables are reduced for credit losses. Such losses are recognized as a reduction of rental revenue in the consolidated statements of operations. Receivables are reviewed monthly and reserves are established with a charge to current period operations when, in the opinion of management, collection of the receivable is doubtful. Accounts receivable in the accompanying consolidated financial statements are shown net of an allowance for doubtful accounts of $0.4 million and $0.6 million , at December 31, 2019 and 2018 , respectively. In addition to rents due currently, accounts receivable also includes $42.1 million and $43.3 million , at December 31, 2019 and 2018 , respectively, net of allowance for doubtful accounts totaling $30,000 and $58,500 , respectively, representing minimum rental income accrued on a straight-line basis to be paid by tenants over the remaining term of their respective leases. Deferred Leasing Costs Deferred leasing costs consist of commissions paid to third-party leasing agents, internal direct costs such as employee compensation and payroll-related fringe benefits directly related to time spent performing leasing-related activities for successful commercial leases and amounts attributed to in place leases associated with acquired properties and are amortized, using the straight-line method, over the term of the lease or the remaining term of an acquired lease. Leasing related activities include evaluating the prospective tenant’s financial condition, evaluating and recording guarantees, collateral and other security arrangements, negotiating lease terms, preparing lease documents and closing the transaction. Unamortized deferred costs are charged to expense if the applicable lease is terminated prior to expiration of the initial lease term. Collectively, deferred leasing costs totaled $24.1 million and $28.1 million , net of accumulated amortization of approximately $41.6 million and $37.7 million , as of December 31, 2019 and 2018 , respectively. Amortization expense, which is included in Depreciation and amortization of deferred leasing costs in the Consolidated Statements of Operations, totaled approximately $5.8 million , $6.1 million , and $5.5 million , for the years ended December 31, 2019 , 2018 , and 2017 , respectively. Cash and Cash Equivalents Cash and cash equivalents include short-term investments. Short-term investments include money market accounts and other investments which generally mature within three months, measured from the acquisition date, and/or are readily convertible to cash. Substantially all of the Company’s cash balances at December 31, 2019 are held in non-interest bearing accounts at various banks. From time to time the Company may maintain deposits with financial institutions in amounts in excess of federally insured limits. The Company has not experienced any losses on such deposits and believes it is not exposed to any significant credit risk on those deposits. Deferred Income Deferred income consists of payments received from tenants prior to the time they are earned and recognized by the Company as revenue, including tenant prepayment of rent for future periods, real estate taxes when the taxing jurisdiction has a fiscal year differing from the calendar year reimbursements specified in the lease agreement and tenant construction work provided by the Company. In addition, deferred income includes the fair value of certain below market leases. Derivative Financial Instruments The Company may, when appropriate, employ derivative instruments, such as interest-rate swaps, to mitigate the risk of interest rate fluctuations. The Company does not enter into derivative or other financial instruments for trading or speculative purposes. Derivative financial instruments are carried at fair value as either assets or liabilities on the consolidated balance sheets. For those derivative instruments that qualify, the Company may designate the hedging instrument, based upon the exposure being hedged, as a fair value hedge or a cash flow hedge. Derivative instruments that are designated as a hedge are evaluated to ensure they continue to qualify for hedge accounting. The effective portion of any gain or loss on the hedge instruments is reported as a component of accumulated other comprehensive income (loss) and recognized in earnings within the same line item associated with the forecasted transaction in the same period or periods during which the hedged transaction affects earnings. Any ineffective portion of the change in fair value of a derivative instrument is immediately recognized in earnings. For derivative instruments that do not meet the criteria for hedge accounting, or that qualify and are not designated, changes in fair value are immediately recognized in earnings. Income Taxes The Company made an election to be treated, and intends to continue operating so as to qualify, as a REIT under the Code, commencing with its taxable year ended December 31, 1993 . A REIT generally will not be subject to federal income taxation, provided that distributions to its stockholders equal or exceed its REIT taxable income and complies with certain other requirements. Therefore, no provision has been made for federal income taxes in the accompanying consolidated financial statements. As of December 31, 2019 , the Company had no material unrecognized tax benefits and there exist no potentially significant unrecognized tax benefits which are reasonably expected to occur within the next twelve months. The Company recognizes penalties and interest accrued related to unrecognized tax benefits, if any, as general and administrative expense. No penalties and interest have been accrued in years 2019 , 2018 , and 2017 . The tax basis of the Company’s real estate investments was approximately $1.33 billion and $1.35 billion as of December 31, 2019 and 2018 , respectively. With few exceptions, the Company is no longer subject to U.S. federal, state, and local tax examinations by tax authorities for years before 2016. Legal Contingencies The Company is subject to various legal proceedings and claims that arise in the ordinary course of business, which are generally covered by insurance. Upon determination that a loss is probable to occur and can be reasonably estimated, the estimated amount of the loss is recorded in the financial statements. Recently Issued Accounting Standards In February 2016, the Financial Accounting Standards Board (‘‘FASB’’) issued Accounting Standards Update (‘‘ASU’’) 2016-02, ‘‘Leases’’ (“ASU 2016-02”). ASU 2016-02 amends the existing accounting standards for lease accounting, including requiring lessees to recognize most leases on their balance sheets and making targeted changes to lessor accounting. ASU 2016-02 is effective for annual periods beginning after December 15, 2018, interim periods within those years, and requires a modified retrospective transition approach for all leases existing at the date of initial application, with an option to use certain practical expedients for those existing leases. Upon adoption of ASU 2016-02 effective January 1, 2019, we elected the practical expedient for all leases with respect to lease identification, lease classification, and initial direct costs. We made a policy election not to separate lease and nonlease components and have accounted for each lease component and the related nonlease components together as a single component. There have been no significant changes to our lessor accounting for operating leases as a result of ASU 2016-02. We lease Shopping Centers and Mixed-Use Properties to lessees in exchange for monthly payments that cover rent, and where applicable, reimbursement for property taxes, insurance, and certain property operating expenses. Our leases were determined to be operating leases and generally range in term from one to 15 years . Some of our leases have termination options and/or extension options. Termination options allow the lessee to terminate the lease prior to the end of the lease term, provided certain conditions are met. Termination options generally require advance notification from the lessee and payment of a termination fee. Termination fees are recognized as revenue over the modified lease term. Extension options are subject to terms and conditions stated in the lease. On January 1, 2019, a right of use asset and corresponding lease liability related to our headquarters lease were recorded in other assets and other liabilities, respectively. The lease expires on February 28, 2022, with one option to renew for an additional five years . The right of use asset and corresponding lease liability totaled $1.6 million and $1.6 million , respectively, at December 31, 2019. In June 2016, the FASB issued ASU 2016-13, "Financial Instruments-Credit Losses" ("ASU 2016-13"). ASU 2016-13 replaces the incurred loss impairment methodology with a methodology that reflects expected credit losses and requires consideration of a broader range of information to support credit loss estimates. ASU 2016-13 is effective for annual periods beginning after December 15, 2019, including interim periods within those years. Management has determined that the adoption of ASU 2016-13 will not have a material impact on our consolidated financial statements and related disclosures because the vast majority of the Company's receivables relate to operating leases which are accounted for under ASC 842. In August 2017, the FASB issued ASU 2017-12, “Derivatives and Hedging” (“ASU 2017-12”). ASU 2017-12 amends financial reporting for hedging activities to better align that reporting with risk management activities. ASU 2017-12 expands and refines hedge accounting for both financial and nonfinancial risk components and aligns the recognition and presentation of the effects of the hedging instrument and the hedged item in the financial statements. Effective with the adoption of ASU 2017-12 on January 1, 2019, changes in the fair value of the Company’s interest rate swap related to changes in the cash flow of the hedged item are reported as a component of interest expense and amortization of deferred debt costs in the Statements of Operations. Reclassifications Certain reclassifications have been made to prior years to conform to the presentation used for year ended December 31, 2019

Real Estate

Real Estate	12 Months Ended
	Dec. 31, 2019
Real Estate [Abstract]
Real Estate	REAL ESTATE Construction in Progress Construction in progress includes land, preconstruction and development costs of active projects. Preconstruction costs include legal, zoning and permitting costs and other project carrying costs incurred prior to the commencement of construction. Development costs include direct construction costs and indirect costs incurred subsequent to the start of construction such as architectural, engineering, construction management and carrying costs consisting of interest, real estate taxes and insurance. The following table shows the components of construction in progress. December 31, (in thousands) 2019 2018 The Waycroft $ 255,443 $ 162,176 7316 Wisconsin Avenue 44,638 — Ashbrook Marketplace 19,128 11,124 Other 16,435 12,672 Total $ 335,644 $ 185,972 Acquisitions Burtonsville Town Square In January 2017, the Company purchased for $76.4 million , including acquisition costs, Burtonsville Town Square located in Burtonsville, Maryland . Olney Shopping Center In March 2017, the Company purchased for $3.1 million , including acquisition costs, the land underlying Olney Shopping Center. The land was previously leased by the Company with an annual rent of approximately $56,000 . The purchase price was funded by the revolving credit facility. Ashbrook Marketplace In May 2018, the Company acquired from the Saul Trust, in exchange for 176,680 limited partnership units, approximately 13.7 acres of land located at the intersection of Ashburn Village Boulevard and Russell Branch Parkway in Loudoun County, Virginia. Based on the closing price of the Company's common stock, the land and the limited partnership units were recorded at a value of $8.8 million . Acquisition costs related to the transaction totaled approximately $0.2 million . 7316 Wisconsin Avenue In September 2018, the Company purchased for $35.5 million , plus $0.7 million of acquisition costs, an office building and the underlying ground located at 7316 Wisconsin Avenue in Bethesda, Maryland. In December 2018, the Company purchased for $4.5 million , including acquisition costs, an interest in an adjacent parcel of land and retail building. The purchase price was funded through the Company's credit facility. The Company has executed lease termination agreements with the final two office tenants and, effective September 1, 2019, the asset was removed from service and transferred to construction in progress at its carrying value of $42.6 million . Allocation of Purchase Price of Real Estate Acquired The Company allocates the purchase price of real estate investment properties to various components, such as land, buildings and intangibles related to in-place leases and customer relationships, based on their relative fair values. During 2018, the Company acquired properties that had an aggregate cost of $49.5 million , including acquisition costs. The purchase price was allocated to assets acquired and liabilities assumed based on their relative fair values as shown in the following table. (in thousands) Ashbrook Marketplace 7316 Wisconsin Avenue Total Land $ 8,776 $ 38,662 $ 47,438 Buildings — 979 979 In-place Leases — 886 886 Above Market Rent — 168 168 Below Market Rent — (21 ) (21 ) Total Purchase Price $ 8,776 $ 40,674 $ 49,450 During 2017, the Company purchased one property, Burtonsville Town Square, at a cost of $76.4 million , including acquisition costs. Of the total acquisition cost, $28.4 million was allocated to land, $45.8 million was allocated to buildings, $2.2 million was allocated to in-place leases, $0.6 million was allocated to above-market rent, and $(0.6) million was allocated to below-market rent, based on their relative fair values. The gross carrying amount of lease intangible assets included in deferred leasing costs as of December 31, 2019 and 2018 was $11.7 million and $12.5 million , respectively, and accumulated amortization was $8.5 million and $8.1 million , respectively. Amortization expense totaled $0.9 million , $1.3 million and $1.1 million , for the years ended December 31, 2019 , 2018 , and 2017 , respectively. The gross carrying amount of below market lease intangible liabilities included in deferred income as of December 31, 2019 and 2018 was $24.1 million and $24.8 million , respectively, and accumulated amortization was $13.9 million and $13.1 million , respectively. Accretion income totaled $1.5 million , $1.7 million , and $1.7 million , for the years ended December 31, 2019 , 2018 , and 2017 , respectively. The gross carrying amount of above market lease intangible assets included in accounts receivable as of December 31, 2019 and 2018 was $0.6 million and $0.8 million , respectively, and accumulated amortization was $108,300 and $143,900 , respectively. Amortization expense totaled $109,600 , $110,500 and $31,600 , for the years ended December 31, 2019 , 2018 and 2017 , respectively. The remaining weighted-average amortization period as of December 31, 2019 is 4.5 years, 7.6 years, and 5.3 years for lease acquisition costs, above market leases and below market leases, respectively. As of December 31, 2019 , scheduled amortization of intangible assets and deferred income related to in place leases is as follows: (In thousands) Lease acquisition costs Above market leases Below market leases 2020 $ 708 $ 43 $ 1,434 2021 535 33 1,409 2022 383 33 1,306 2023 317 33 1,297 2024 198 33 878 Thereafter 996 343 3,853 Total $ 3,137 $ 518 $ 10,177

Noncontrolling Interests - Hold

Noncontrolling Interests - Holders of Convertible Limited Partnership Units in the Operating Partnership	12 Months Ended
	Dec. 31, 2019
Noncontrolling Interest [Abstract]
Noncontrolling Interests - Holders of Convertible Limited Partnership Units in the Operating Partnership	NONCONTROLLING INTERESTS - HOLDERS OF CONVERTIBLE LIMITED PARTNERSHIP UNITS IN THE OPERATING PARTNERSHIP Saul Centers is the sole general partner of the Operating Partnership, owning a 74.6% common interest as of December 31, 2019 . Noncontrolling interest in the Operating Partnership is comprised of limited partnership units owned by the Saul Organization. Noncontrolling interest reflected on the accompanying consolidated balance sheets is increased for earnings allocated to limited partnership interests and distributions reinvested in additional units, and is decreased for limited partner distributions. Noncontrolling interest reflected on the consolidated statements of operations represents earnings allocated to limited partnership interests held by the Saul Organization. The Saul Organization holds a 25.4% limited partnership interest in the Operating Partnership represented by 7,886,916 limited partnership units, as of December 31, 2019 . The units are convertible into shares of Saul Centers’ common stock, at the option of the unit holder, on a one -for-one basis provided that, in accordance with the Saul Centers, Inc. Articles of Incorporation, the rights may not be exercised at any time that the Saul Organization beneficially owns, directly or indirectly, in the aggregate more than 39.9% of the value of the outstanding common stock and preferred stock of Saul Centers (the “Equity Securities”). As of December 31, 2019 , approximately 925,000 units were eligible for conversion. The impact of the Saul Organization’s 25.4% limited partnership interest in the Operating Partnership is reflected as Noncontrolling Interests in the accompanying consolidated financial statements. Fully converted partnership units and diluted weighted average shares outstanding for the years ended December 31, 2019 , 2018 , and 2017 , were 30.9 million , 30.2 million , and 29.5 million , respectively.

Mortgage Notes Payable, Revolvi

Mortgage Notes Payable, Revolving Credit Facility, Interest Expense and Amortization of Deferred Debt Costs	12 Months Ended
	Dec. 31, 2019
Debt Disclosure [Abstract]
Mortgage Notes Payable, Revolving Credit Facility, Interest Expense and Amortization of Deferred Debt Costs	MORTGAGE NOTES PAYABLE, REVOLVING CREDIT FACILITY, INTEREST EXPENSE AND AMORTIZATION OF DEFERRED DEBT COSTS At December 31, 2019 , the principal amount of outstanding debt totaled $1.1 billion , of which $938.4 million was fixed rate debt and $162.5 million was variable rate debt. The principal amount of the Company’s outstanding debt totaled $1.0 billion at December 31, 2018 , of which $910.2 million was fixed rate debt and $122.0 million was variable rate debt. At December 31, 2019 , the Company had a $400.0 million unsecured credit facility, which can be used for working capital, property acquisitions or development projects, of which $325.0 million is a revolving credit facility and $75.0 million is a term loan. The revolving credit facility matures on January 26, 2022, and may be extended by the Company for one additional year subject to the Company’s satisfaction of certain conditions. The term loan matures on January 26, 2023, and may not be extended. Saul Centers and certain consolidated subsidiaries of the Operating Partnership have guaranteed the payment obligations of the Operating Partnership under the credit facility. Letters of credit may be issued under the revolving credit facility. On December 31, 2019 , based on the value of the Company's unencumbered properties, approximately $237.3 million was available under the revolving credit facility, $87.5 million was outstanding and approximately $185,000 was committed for letters of credit. Interest at a rate equal to the sum of one-month LIBOR and a margin that is based on the Company’s leverage ratio and which can range from 135 basis points to 195 basis points under the revolving facility and from 130 basis points to 190 basis points under the term loan. As of December 31, 2019 , the margin was 135 basis points under the revolving facility and 130 basis points under the term loan. Saul Centers is a guarantor of the credit facility, of which the Operating Partnership is the borrower. The Operating Partnership is the guarantor of (a) a portion of the Park Van Ness mortgage (approximately $6.7 million of the $68.1 million outstanding balance at December 31, 2019 , which guarantee will be reduced to (i) $3.3 million on October 1, 2020 and (ii) zero on October 1, 2021), (b) a portion of the Kentlands Square II mortgage (approximately $8.5 million of the $34.0 million outstanding balance at December 31, 2019 ), (c) a portion of the Broadlands mortgage (approximately $3.9 million of the $31.2 million outstanding balance at December 31, 2019 ), and (d) a portion of the Avenel Business Park mortgage (approximately $6.3 million of the $26.3 million outstanding balance at December 31, 2019 ). All other notes payable are non-recourse. On January 18, 2017 , the Company closed on a 15 -year, non-recourse $40.0 million mortgage loan secured by Burtonsville Town Square. The loan matures in 2032 , bears interest at a fixed rate of 3.39% , requires monthly principal and interest payments of $197,900 based on a 25 -year amortization schedule and requires a final payment of $20.3 million at maturity. On August 14, 2017, the Company closed on a $157.0 million construction-to-permanent loan, the proceeds of which will be used to partially fund The Waycroft development project. The loan matures in 2035, bears interest at a fixed rate of 4.67% , requires interest only payments, which will be funded by the loan, until conversion to permanent. The conversion is expected in the fourth quarter of 2021, and thereafter, monthly principal and interest payments of $887,900 based on a 25 -year amortization schedule will be required. Effective September 1, 2017 , the Company's $71.6 million construction-to-permanent loan, which is fully drawn and secured by Park Van Ness, converted to permanent financing. The loan matures in 2032 , bears interest at a fixed rate of 4.88% , requires monthly principal and interest payments of $413,460 based on a 25 -year amortization schedule and requires a final payment of $39.6 million at maturity. On November 20, 2017 , the Company closed on a 15 -year, non-recourse $60.0 million mortgage loan secured by Washington Square. The loan matures in 2032 , bears interest at a fixed rate of 3.75% , requires monthly principal and interest payments of $308,500 based on a 25 -year amortization schedule and requires a final payment of $31.1 million . Proceeds were used to repay the remaining balance of approximately $28.1 million on the existing mortgage and reduce the outstanding balance of the revolving credit facility. On October 3, 2018 , the Company closed on a 15 -year , non-recourse $32.0 million mortgage loan secured by Broadlands Village. The loan matures in 2033 , bears interest at a fixed-rate of 4.41% , requires monthly principal and interest payments of $176,200 based on a 25 -year amortization schedule and requires a final payment of $17.3 million at maturity. Proceeds were used to repay the remaining principal balance of approximately $15.2 million on the existing mortgage, the remaining balance of approximately $7.3 million on the existing mortgage collateralized by the Glen, the remaining balance of approximately $6.1 million on the existing mortgage collateralized by Kentlands Square I, and reduce the outstanding balance of the revolving credit facility. On December 18, 2018 , the Company closed on a 15 -year, non-recourse $22.9 million mortgage loan secured by The Glen. The loan matures in 2034 , bears interest at a fixed-rate of 4.69% , requires monthly principal and interest payments of $129,800 based on a 25 -year amortization schedule and requires a final payment of $12.5 million at maturity. On January 4, 2019, the Company repaid in full the remaining principal balance of $12.7 million of the mortgage loan secured by Countryside Marketplace, which was scheduled to mature in July 2019. On January 10, 2019, the Company closed on a 15 -year, non-recourse $22.1 million mortgage loan secured by Olde Forte Village. The loan matures in 2034, bears interest at a fixed-rate of 4.65% , requires monthly principal and interest payments of $124,700 based on a 25 -year amortization schedule and requires a final payment of $12.1 million . Proceeds were partially used to repay in full the existing mortgage secured by Olde Forte Village, which was scheduled to mature in May 2019. On June 3, 2019, the Company repaid in full the remaining principal balance of $12.4 million of the mortgage loan secured by Briggs Chaney Marketplace, which was scheduled to mature in September 2019. On November 12, 2019, the Company closed on a 15 -year, non-recourse $28.5 million mortgage loan secured by Shops at Monocacy. The loan matures in 2034, bears interest at a fixed-rate of 4.14% , requires monthly principal and interest payments of $152,600 based on a 25 -year amortization schedule and requires a final payment of $15.1 million . Proceeds were partially used to repay in full the existing mortgage secured by Shops at Monocacy, which was scheduled to mature in January 2020. On November 21, 2019, the Company repaid in full the remaining principal balance of $35.6 million of the mortgage loan secured by Thruway, which was scheduled to mature in July 2020. The Company’s corresponding swap agreement was terminated on the same day. The carrying value of the properties collateralizing the mortgage notes payable totaled $1.1 billion and $1.1 billion , as of December 31, 2019 and 2018 , respectively. The Company’s credit facility requires the Company and its subsidiaries to maintain certain financial covenants, which are summarized below. The Company was in compliance as of December 31, 2019 . • limit the amount of debt as a percentage of gross asset value, as defined in the loan agreement, to less than 60% (leverage ratio); • limit the amount of debt so that interest coverage will exceed 2.0 x on a trailing four-quarter basis (interest expense coverage); and • limit the amount of debt so that interest, scheduled principal amortization and preferred dividend coverage exceeds 1.4 x on a trailing four-quarter basis (fixed charge coverage). Mortgage notes payable at December 31, 2019 and 2018 , totaling $41.0 million and $51.0 million , respectively, are guaranteed by members of the Saul Organization. As of December 31, 2019 , the scheduled maturities of all debt including scheduled principal amortization for years ended December 31 are as follows: (in thousands) Balloon Payments Scheduled Principal Amortization Total 2020 $ 16,074 $ 28,421 $ 44,495 2021 11,012 29,025 40,037 2022 124,002 (a) 29,645 153,647 2023 84,225 30,065 114,290 2024 66,649 28,697 95,346 Thereafter 527,297 125,809 653,106 Principal amount $ 829,259 $ 271,662 1,100,921 Unamortized deferred debt costs 9,733 Net $ 1,091,188 (a) Includes $87.5 million outstanding under the revolving facility. Deferred Debt Costs Deferred debt costs consist of fees and costs incurred to obtain long-term financing, construction financing and the revolving line of credit. These fees and costs are being amortized on a straight-line basis over the terms of the respective loans or agreements, which approximates the effective interest method. Deferred debt costs totaled $9.7 million and $10.3 million , net of accumulated amortization of $7.5 million and $7.3 million at December 31, 2019 and 2018 , respectively, and are reflected as a reduction of the related debt in the Consolidated Balance Sheets. The components of interest expense are set forth below. (in thousands) Year ended December 31, 2019 2018 2017 Interest incurred $ 52,044 $ 49,652 $ 49,322 Amortization of deferred debt costs 1,518 1,610 1,392 Capitalized interest (11,480 ) (6,222 ) (3,489 ) Interest expense 42,082 45,040 47,225 Less: Interest income 248 272 80 Interest expense, net and amortization of deferred debt costs $ 41,834 $ 44,768 $ 47,145 Deferred debt costs capitalized during the years ending December 31, 2019 , 2018 and 2017 totaled $1.0 million , $3.2 million and $2.6 million , respectively.

Lease Agreements

Lease Agreements	12 Months Ended
	Dec. 31, 2019
Leases [Abstract]
Lease Agreements	LEASE AGREEMENTS Lease income includes primarily base rent arising from noncancelable leases. Base rent (including straight-line rent) for the years ended December 31, 2019 , 2018 , and 2017 , amounted to $185.7 million , $184.7 million , and $181.1 million , respectively. Future contractual payments under noncancelable leases for years ended December 31 (which exclude the effect of straight-line rents), are as follows: (in thousands) 2020 $ 166,227 2021 149,949 2022 126,101 2023 104,489 2024 75,172 Thereafter 260,141 $ 882,079 The majority of the leases provide for rental increases based on fixed annual increases or increases in the Consumer Price Index and expense recoveries based on increases in operating expenses. The expense recoveries generally are payable in equal installments throughout the year based on estimates, with adjustments made in the succeeding year. Expense recoveries for the years ended December 31, 2019 , 2018 , and 2017 , amounted to $36.5 million , $35.5 million , and $35.3 million , respectively. In addition, certain retail leases provide for percentage rent based on sales in excess of the minimum specified in the tenant’s lease. Percentage rent amounted to $0.9 million , $1.0 million , and $1.5 million , for the years ended December 31, 2019 , 2018 , and 2017 , respectively.

Long-Term Lease Obligations

Long-Term Lease Obligations	12 Months Ended
	Dec. 31, 2019
Leases [Abstract]
Long-Term Lease Obligations	LONG-TERM LEASE OBLIGATIONS At December 31, 2018 and 2019, no properties are subject to noncancelable long-term leases which apply to underlying land. Flagship Center consists of two developed out parcels that are part of a larger adjacent community shopping center formerly owned by the Saul Organization and sold to an affiliate of a tenant in 1991. The Company has a 90 -year ground leasehold interest which commenced in September 1991 with a minimum rent of one dollar per year. Countryside shopping center was acquired in February 2004. Because of certain land use considerations, approximately 3.4% of the underlying land is held under a 99 -year ground lease. The lease requires the Company to pay minimum rent of one dollar per year as well as its pro-rata share of the real estate taxes. The Company’s corporate headquarters space is leased by a member of the Saul Organization. The lease commenced in March 2002, and expires in February 2022. The Company and the Saul Organization entered into a Shared Services Agreement whereby each party pays an allocation of total rental payments based on a percentage proportionate to the number of employees employed by each party. The Company’s rent expense for the years ended December 31, 2019 , 2018 , and 2017 was $806,500 , $779,800 , and $774,700 , respectively. Expenses arising from the lease are included in general and administrative expense (see Note 9 – Related Party Transactions).

Equity and Noncontrolling Inter

Equity and Noncontrolling Interest	12 Months Ended
	Dec. 31, 2019
Noncontrolling Interest [Abstract]
Equity and Noncontrolling Interest	EQUITY AND NONCONTROLLING INTEREST The Consolidated Statements of Operations for the years ended December 31, 2019 , 2018 , and 2017 reflect noncontrolling interest of $12.5 million , $12.5 million , and $12.4 million , respectively, representing the Saul Organization’s share of the net income for the year. At December 31, 2019, the Company had outstanding 3.0 million depositary shares, each representing 1/100th of a share of 6.125% Series D Cumulative Redeemable Preferred Stock (the "Series D Stock"). The depositary shares may be redeemed at the Company’s option, in whole or in part, on or after January 23, 2023, at the $25.00 liquidation preference, plus accrued but unpaid dividends to but not including the redemption date. The depositary shares pay an annual dividend of $1.53125 per share, equivalent to 6.125% of the $25.00 liquidation preference. The Series D Stock has no stated maturity, is not subject to any sinking fund or mandatory redemption and is not convertible into any other securities of the Company except in connection with certain changes in control or delisting events. Investors in the depositary shares generally have no voting rights, but will have limited voting rights if the Company fails to pay dividends for six or more quarters (whether or not declared or consecutive) and in certain other events. On September 17, 2019, Saul Centers sold, in an underwritten public offering, 4.0 million depositary shares, each representing 1/100th of a share of 6.000% Series E Cumulative Redeemable Preferred Stock (the “Series E Stock”), providing net cash proceeds of approximately $96.8 million . The depositary shares may be redeemed in whole or in part, on or after September 17, 2024, at the $25.00 liquidation preference, plus accrued but unpaid dividends to but not including the redemption date. The depositary shares pay an annual dividend of $1.50 per share, equivalent to 6.000% of the $25.00 liquidation preference. The Series E Stock has no stated maturity, is not subject to any sinking fund or mandatory redemption and is not convertible into any other securities of the Company except in connection with certain changes in control or delisting events. Investors in the depositary shares generally have no voting rights, but will have limited voting rights if the Company fails to pay dividends for six or more quarters (whether or not declared or consecutive) and in certain other events. On September 23, 2019, Saul Centers sold, as a result of the exercise by the underwriters of their over-allotment option, an additional 0.4 million depositary shares of Series E Stock, providing net cash proceeds of approximately $9.5 million . At December 31, 2018, the Company had outstanding 4.2 million depositary shares, each representing 1/100th of a share of 6.875% Series C Cumulative Redeemable Preferred Stock (the “Series C Stock”). The depositary shares are redeemable at the Company’s option, in whole or in part, at the $25.00 liquidation preference plus accrued but unpaid dividends. The depositary shares pay an annual dividend of $1.71875 per share, equivalent to 6.875% of the $25.00 liquidation preference. The Series C Stock has no stated maturity, is not subject to any sinking fund or mandatory redemption and is not convertible into any other securities of the Company except in connection with certain changes of control or delisting events. Investors in the depositary shares generally have no voting rights, but will have limited voting rights if the Company fails to pay dividends for six or more quarters (whether or not declared or consecutive) and in certain other events. In September 2019, the Company announced the redemption of all outstanding depositary shares representing interests in its Series C Stock. The depositary shares were redeemed on October 17, 2019 at $25.00 per depositary share, plus all accrued and unpaid dividends to, but not including, the redemption date, for an aggregate redemption price of $25.07638 per depositary share. In the fourth quarter, costs associated with the redemption were charged against Net income available to common stockholders. After the redemption date, dividends on the depositary shares representing interests in the Series C Stock ceased to accrue. Per Share Data Per share data for net income (basic and diluted) is computed using weighted average shares of common stock. Convertible limited partnership units and employee stock options are the Company’s potentially dilutive securities. For all periods presented, the convertible limited partnership units are anti-dilutive. The treasury stock method was used to measure the effect of the dilution. December 31, (Shares in thousands) 2019 2018 2017 Weighted average common shares outstanding - Basic 23,009 22,383 21,901 Effect of dilutive options 44 42 107 Weighted average common shares outstanding - Diluted 23,053 22,425 22,008 Average share price $ 53.41 $ 52.50 $ 61.63 Non-dilutive options 633 492 — Years non-dilutive options were issued 2016, 2017 and 2019 2015, 2016 and 2017

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2019
Related Party Transactions [Abstract]
Related Party Transactions	RELATED PARTY TRANSACTIONS The Chairman, Chief Executive Officer and President, the Executive Vice President of Real Estate, the Executive Vice President-Chief Legal and Administrative Officer and the Senior Vice President-Chief Accounting Officer of the Company are also officers of various members of the Saul Organization and their management time is shared with the Saul Organization. Their annual compensation is fixed by the Compensation Committee of the Board of Directors, with the exception of the Senior Vice President-Chief Accounting Officer whose share of annual compensation allocated to the Company is determined by the shared services agreement (described below). The Company participates in a multiemployer 401K plan with entities in the Saul Organization which covers those full-time employees who meet the requirements as specified in the plan. Company contributions, which are included in general and administrative expense or property operating expenses in the consolidated statements of operations, at the discretionary amount of up to six percent of the employee’s cash compensation, subject to certain limits, were $322,200 , $345,900 , and $349,500 , for 2019 , 2018 , and 2017 , respectively. All amounts deferred by employees and contributed by the Company are fully vested. The Company also participates in a multiemployer nonqualified deferred compensation plan with entities in the Saul Organization which covers those full-time employees who meet the requirements as specified in the plan. According to the plan, which can be modified or discontinued at any time, participating employees defer 2% of their compensation in excess of a specified amount. For the years ended December 31, 2019 , 2018 , and 2017 , the Company contributed three times the amount deferred by employees. The Company’s expense, included in general and administrative expense, totaled $345,200 , $282,500 , and $228,500 , for the years ended December 31, 2019 , 2018 , and 2017 , respectively. All amounts deferred by employees and the Company are fully vested. The cumulative unfunded liability under this plan was $3.1 million and $2.7 million , at December 31, 2019 and 2018 , respectively, and is included in accounts payable, accrued expenses and other liabilities in the consolidated balance sheets. The Company has entered into a shared services agreement (the “Agreement”) with the Saul Organization that provides for the sharing of certain personnel and ancillary functions such as computer hardware, software, and support services and certain direct and indirect administrative personnel. The method for determining the cost of the shared services is provided for in the Agreement and is based upon head count, estimates of usage or estimates of time incurred, as applicable. Senior management has determined that the final allocations of shared costs are reasonable. The terms of the Agreement and the payments made thereunder are reviewed annually by the Audit Committee of the Board of Directors, which consists entirely of independent directors. Net billings by the Saul Organization for the Company’s share of these ancillary costs and expenses for the years ended December 31, 2019 , 2018 , and 2017 , which included rental expense for the Company’s headquarters lease (see Note 7. Long Term Lease Obligations), totaled $8.4 million , $8.4 million , and $8.1 million , respectively. The amounts are expensed when incurred and are primarily reported as general and administrative expenses or capitalized to specific development projects in these consolidated financial statements. As of December 31, 2019 and 2018 , accounts payable, accrued expenses and other liabilities included $918,700 and $933,400 , respectively, representing billings due to the Saul Organization for the Company’s share of these ancillary costs and expenses. The Company has entered into a shared third-party predevelopment cost agreement with the Saul Trust (the “Predevelopment Agreement”). The Predevelopment Agreement, which expired on December 31, 2015 and was extended to December 31, 2016, relates to the sharing of third-party predevelopment costs incurred in connection with the planning of the future redevelopment of certain adjacent real estate assets in the Twinbrook area of Rockville, Maryland. On December 8, 2016, the Company entered into a replacement agreement with the Saul Trust which extended the expiration date to December 31, 2017 and provides for automatic twelve month renewals unless either party provides notice of termination. The costs will be shared on a pro rata basis based on the acreage owned by each entity and neither party is obligated to advance funds to the other. On November 5, 2019, the Company entered into an agreement (the "Contribution Agreement") to acquire from the Saul Trust, approximately 6.8 acres of land and its leasehold interest in approximately 1.3 acres of contiguous land, together in each case with the improvements located thereon, located at the Twinbrook Metro Station in Rockville, Maryland (the “Contributed Property”). In exchange for the Contributed Property, the Company will issue to the Saul Trust 1,416,071 limited partnership units in the Operating Partnership (“OP Units”) at an agreed upon value of $56.00 per OP Unit, representing an aggregate value of $79.3 million for the Contributed Property. Deed to the Contributed Property and the OP Units have been placed in escrow until certain conditions of the Contribution Agreement are satisfied. The B. F. Saul Insurance Agency of Maryland, Inc., a subsidiary of the B. F. Saul Company and a member of the Saul Organization, is a general insurance agency that receives commissions and counter-signature fees in connection with the Company’s insurance program. Such commissions and fees amounted to approximately $399,600 , $407,900 , and $288,400 , for the years ended December 31, 2019 , 2018 , and 2017 , respectively. In August 2016, the Company entered into an agreement to acquire from the Saul Trust, approximately 13.7 acres of land located at the intersection of Ashburn Village Boulevard and Russell Branch Parkway in Ashburn, Virginia. The transaction closed on May 9, 2018, and the Company issued 176,680 limited partnership units to the Saul Trust. The Company intends to construct a shopping center and, upon stabilization, may be obligated to issue additional limited partnership units to the Saul Trust.

Stock Option Plan

Stock Option Plan	12 Months Ended
	Dec. 31, 2019
Share-based Payment Arrangement [Abstract]
Stock Option Plan	STOCK OPTION PLAN Stock Based Employee Compensation, Deferred Compensation and Stock Plan for Directors In 2004, the Company established a stock incentive plan (the "Plan"), as amended. Under the Plan, options were granted at an exercise price not less than the market value of the common stock on the date of grant and expire ten years from the date of grant. Officer options vest ratably over four years following the grant and are charged to expense using the straight-line method over the vesting period. Director options vest immediately and are charged to expense as of the date of grant. The Company uses the fair value method to value and account for employee stock options. The fair value of options granted is determined at the time of each award using the Black-Scholes model, a widely used method for valuing stock-based employee compensation, and the following assumptions: (1) Expected Volatility determined using the most recent trading history of the Company’s common stock (month-end closing prices) corresponding to the average expected term of the options; (2) Average Expected Term of the options is based on prior exercise history, scheduled vesting and the expiration date; (3) Expected Dividend Yield determined by management after considering the Company’s current and historic dividend yield rates, the Company’s yield in relation to other retail REITs and the Company’s market yield at the grant date; and (4) a Risk-free Interest Rate based upon the market yields of US Treasury obligations with maturities corresponding to the average expected term of the options at the grant date. The Company amortizes the value of options granted ratably over the vesting period and includes the amounts as compensation expense in general and administrative expenses. Pursuant to the Plan, the Compensation Committee established a Deferred Compensation Plan for Directors for the benefit of the Company’s directors and their beneficiaries, which replaced a previous Deferred Compensation and Stock Plan for Directors. Annually, directors are given the ability to make an election to defer all or part of their fees and have the option to have their fees paid in cash, in shares of common stock or in a combination of cash and shares of common stock upon separation from the Board. If a director elects to their have fees paid in stock, fees earned during a calendar quarter are aggregated and divided by the closing market price of the Company’s common stock on the first trading day of the following quarter to determine the number of shares to be credited to the director. During the twelve months ended December 31, 2019 , 6,822 shares were credited to director's deferred fee accounts and 7,058 shares were issued. As of December 31, 2019 , the director's deferred fee accounts comprise 114,408 shares. The Compensation Committee has also approved an annual award of shares of the Company’s common stock as additional compensation to each director serving on the Board of Directors as of the record date for the Annual Meeting of Stockholders. The shares are awarded as of each Annual Meeting of Stockholders, and their issuance may not be deferred. At the annual meeting of the Company’s stockholders in 2004, the stockholders approved the adoption of the 2004 stock plan for the purpose of attracting and retaining executive officers, directors and other key personnel. The 2004 stock plan was subsequently amended by the Company’s stockholders at the 2008 Annual Meeting, further amended at the 2013 Annual Meeting, and further amended at the 2019 Annual Meeting (the “Amended 2004 Plan”). The Amended 2004 Plan, which terminates in 2029, provides for grants of options to purchase up to 3,400,000 shares of common stock. The Amended 2004 Plan authorizes the Compensation Committee of the Board of Directors to grant options at an exercise price which may not be less than the market value of the common stock on the date the option is granted. Effective May 5, 2017 , the Compensation Committee granted options to purchase 232,500 shares ( 21,492 incentive stock options and 211,008 nonqualified stock options) to 20 Company officers and 11 Company Directors (the “2017 options”), which expire on May 4, 2027 . The officers’ 2017 Options vest 25% per year over four years and are subject to early expiration upon termination of employment. The directors’ 2017 Options were immediately exercisable. The exercise price of $59.41 per share was the closing market price of the Company’s common stock on the date of award. Using the Black-Scholes model, the Company determined the total fair value of the 2017 Options to be $1.4 million , of which $1.2 million and $165,600 were assigned to the officer options and director options, respectively. Because the directors’ options vested immediately, the entire $165,600 was expensed as of the date of grant. The expense for the officers’ options is being recognized as compensation expense monthly during the four years the options vest. Effective May 11, 2018 , the Compensation Committee granted options to purchase 245,000 shares ( 25,914 incentive stock options and 219,086 nonqualified stock options) to 22 Company officers and 11 Company Directors (the “2018 options”), which expire on May 10, 2028 . The officers’ 2018 Options vest 25% per year over four years and are subject to early expiration upon termination of employment. The directors’ 2018 Options were immediately exercisable. The exercise price of $49.46 per share was the closing market price of the Company’s common stock on the date of award. Using the Black-Scholes model, the Company determined the total fair value of the 2018 Options to be $1.4 million , of which $1.2 million and $169,400 were assigned to the officer options and director options, respectively. Because the directors’ options vested immediately, the entire $169,400 was expensed as of the date of grant. The expense for the officers’ options is being recognized as compensation expense monthly during the four years the options vest. Effective May 3, 2019 , the Compensation Committee granted options to purchase 260,000 shares ( 34,651 incentive stock options and 225,349 nonqualified stock options) to 23 Company officers and 11 Company Directors (the “2019 options”), which expire on May 2, 2029 . The officers’ 2019 Options vest 25% per year over four years and are subject to early expiration upon termination of employment. The directors’ 2018 Options were immediately exercisable. The exercise price of $55.71 per share was the closing market price of the Company’s common stock on the date of award. Using the Black-Scholes model, the Company determined the total fair value of the 2019 Options to be $1.9 million , of which $1.7 million and $226,600 were assigned to the officer options and director options, respectively. Because the directors’ options vested immediately, the entire $226,600 was expensed as of the date of grant. The expense for the officers’ options is being recognized as compensation expense monthly during the four years the options vest. The following table summarizes the assumptions used in the valuation of the 2017, 2018, and 2019 option grants. During the twelve months ended December 31, 2019 , stock option expense totaling $1.6 million was included in general and administrative expense in the Consolidated Statements of Operations. As of December 31, 2019 , the estimated future expense related to unvested stock options was $2.6 million . Directors Officers Grant date May 5, 2017 May 11, 2018 May 3, 2019 May 5, 2017 May 11, 2018 May 3, 2019 Exercise price $ 59.41 $ 49.46 $ 55.71 $ 59.41 $ 49.46 $ 55.71 Volatility 0.173 0.192 0.236 0.170 0.177 0.206 Expected life (years) 5.0 5.0 5.0 7.0 7.0 7.0 Assumed yield 3.45 % 3.70 % 3.75 % 3.50 % 3.75 % 3.80 % Risk-free rate 1.89 % 2.84 % 2.33 % 2.17 % 2.94 % 2.43 % The table below summarizes the option activity for the years 2019 , 2018 , and 2017 : 2019 2018 2017 Shares Weighted Shares Weighted Shares Weighted Outstanding at January 1 1,114,169 $ 52.40 913,320 $ 52.80 833,630 $ 49.92 Granted 260,000 55.71 245,000 49.46 232,500 59.41 Exercised (57,055 ) 44.53 (39,151 ) 42.98 (149,060 ) 46.97 Expired/Forfeited (7,500 ) 56.07 (5,000 ) 54.78 (3,750 ) 53.73 Outstanding December 31 1,309,614 53.38 1,114,169 52.40 913,320 52.80 Exercisable at December 31 763,614 52.43 600,919 50.93 430,945 48.94 The intrinsic value of options exercised in 2019 , 2018 , and 2017 , was $0.6 million , $0.5 million and $2.2 million , respectively. The intrinsic value of options outstanding and exercisable at year end 2019 was $2.5 million and $2.0 million , respectively. The intrinsic value measures the difference between the options’ exercise price and the closing share price quoted by the New York Stock Exchange as of the date of measurement. The date of exercise was the measurement date for shares exercised during the period. At December 31, 2019 , the final trading day of calendar 2019 , the closing price of $52.78 per share was used for the calculation of aggregate intrinsic value of options outstanding and exercisable at that date. The weighted average remaining contractual life of the Company’s exercisable and outstanding options at December 31, 2019 are 5.9 and 7.0 years, respectively.

Fair Value of Financial Instrum

Fair Value of Financial Instruments	12 Months Ended
	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	FAIR VALUE OF FINANCIAL INSTRUMENTS The carrying values of cash and cash equivalents, accounts receivable, accounts payable and accrued expenses and floating rate debt are reasonable estimates of their fair value. The aggregate fair value of the notes payable with fixed-rate payment terms was determined using Level 3 data in a discounted cash flow approach, which is based upon management’s estimate of borrowing rates and loan terms currently available to the Company for fixed rate financing, and assuming long term interest rates of approximately 3.55% and 4.40% , would be approximately $957.4 million and $927.0 million as of December 31, 2019 and 2018 , respectively, compared to the principal balance of $938.4 million and $910.2 million at December 31, 2019 and 2018 , respectively. A change in any of the significant inputs may lead to a change in the Company’s fair value measurement of its debt.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	COMMITMENTS AND CONTINGENCIES Neither the Company nor the Current Portfolio Properties are subject to any material litigation, nor, to management’s knowledge, is any material litigation currently threatened against the Company, other than routine litigation and administrative proceedings arising in the ordinary course of business. Management believes that these items, individually or in the aggregate, will not have a material adverse impact on the Company or the Current Portfolio Properties.

Distributions

Distributions	12 Months Ended
	Dec. 31, 2019
Equity [Abstract]
Distributions	DISTRIBUTIONS In December 1995, the Company established a Dividend Reinvestment and Stock Purchase Plan (the “Plan”), to allow its stockholders and holders of limited partnership interests an opportunity to buy additional shares of common stock by reinvesting all or a portion of their dividends or distributions. The Plan provides for investing in newly issued shares of common stock at a 3% discount from market price without payment of any brokerage commissions, service charges or other expenses. All expenses of the Plan are paid by the Company. The Operating Partnership also maintains a similar dividend reinvestment plan that mirrors the Plan, which allows holders of limited partnership interests the opportunity to buy either additional limited partnership units or common stock shares of the Company. The Company paid common stock distributions of $2.12 per share in 2019 , $2.08 per share in 2018 , and $2.04 per share in 2017 , Series C preferred stock dividends of $1.80 , $1.72 , and $1.72 , respectively, per depositary share during each of 2019 , 2018 , and 2017 , Series D preferred stock dividends of $1.53 and $1.05 , respectively, per depositary share in 2019 and 2018, and Series E preferred stock dividends of $0.06 per depositary share in 2019 . Of the common stock dividends paid, $2.00 per share, $1.61 per share, and $1.70 per share, represented ordinary dividend income in 2019 , 2018 , and 2017 , respectively, and $0.12 per share, $0.47 per share, and $0.34 per share represented return of capital to the shareholders in 2019 , 2018 , and 2017 , respectively. All of the preferred stock dividends paid were considered ordinary dividend income. The following summarizes distributions paid during the years ended December 31, 2019 , 2018 , and 2017 , and includes activity in the Plan as well as limited partnership units issued from the reinvestment of unit distributions: Total Distributions to Dividend Reinvestments (Dollars in thousands, except per share amounts) Preferred Common Limited Common Discounted Limited Partnership Units Issued Average Unit Price Distributions during 2019 4th Quarter $ 3,531 $ 12,251 $ 4,173 104,558 $ 52.84 13,747 $ 53.73 3rd Quarter 2,953 12,195 4,166 105,753 53.66 13,406 54.56 2nd Quarter 2,953 12,116 4,155 99,804 51.38 20,041 51.99 1st Quarter 2,953 12,006 4,148 120,347 51.28 13,742 52.16 Total 2019 $ 12,390 $ 48,568 $ 16,642 430,462 60,936 Distributions during 2018 4th Quarter $ 2,953 $ 11,706 $ 4,062 216,476 $ 49.34 13,867 $ 50.20 3rd Quarter 2,953 11,590 4,055 201,500 51.68 13,107 52.60 2nd Quarter 2,672 11,545 3,942 85,202 47.54 42,422 47.83 1st Quarter 3,824 11,465 3,922 69,750 52.71 38,037 53.03 Total 2018 $ 12,402 $ 46,306 $ 15,981 572,928 107,433 Distributions during 2017 4th Quarter $ 3,094 $ 11,221 $ 3,838 82,991 $ 59.33 15,596 $ 60.08 3rd Quarter 3,094 11,160 3,830 85,731 57.40 16,021 58.13 2nd Quarter 3,094 11,119 3,810 51,003 59.64 40,623 59.96 1st Quarter 3,093 11,076 3,790 46,286 61.85 39,111 62.15 Total 2017 $ 12,375 $ 44,576 $ 15,268 266,011 111,351 In December 2019 , the Board of Directors of the Company authorized a distribution of $0.53 per common share payable in January 2020 to holders of record on January 17, 2020 . As a result, $12.3 million was paid to common shareholders on January 31, 2020 . Also, $4.2 million was paid to limited partnership unitholders on January 31, 2020 ( $0.53 per Operating Partnership unit). The Board of Directors authorized preferred stock dividends of (a) $0.3750 per Series E depositary share and (b) $0.3828 per Series D depositary share to holders of record on January 2, 2020 . As a result, $2.8 million was paid to preferred shareholders on January 15, 2020 . These amounts are reflected as a reduction of stockholders’ equity in the case of common stock and preferred stock dividends and noncontrolling interests deductions in the case of limited partner distributions and are included in dividends and distributions payable in the accompanying consolidated financial statements.

Interim Results (Unaudited)

Interim Results (Unaudited)	12 Months Ended
	Dec. 31, 2019
Quarterly Financial Information Disclosure [Abstract]
Interim Results (Unaudited)	INTERIM RESULTS (Unaudited) The following summary presents the results of operations of the Company for the quarterly periods of calendar years 2019 and 2018 . (In thousands, except per share amounts) 2019 1st Quarter 2nd Quarter 3rd Quarter 4th Quarter Total revenue $ 59,750 $ 58,141 $ 57,052 $ 56,582 Net Income 17,077 16,750 15,328 15,041 Net income attributable to Saul Centers, Inc. 13,447 13,232 12,226 12,818 Net income available to common stockholders 10,494 10,279 9,016 6,464 Net income available to common stockholders per diluted share 0.46 0.45 0.39 0.27 (In thousands, except per share amounts) 2018 1st Quarter 2nd Quarter 3rd Quarter 4th Quarter Total revenue $ 56,109 $ 56,081 $ 56,910 $ 58,119 Net Income 14,946 15,902 16,702 15,509 Net income attributable to Saul Centers, Inc. 12,587 12,543 13,155 12,269 Net income available to common stockholders 6,856 9,590 10,202 9,316 Net income available to common stockholders per diluted share 0.31 0.43 0.45 0.41

Business Segments

Business Segments	12 Months Ended
	Dec. 31, 2019
Segment Reporting [Abstract]
Business Segments	BUSINESS SEGMENTS The Company has two reportable business segments: Shopping Centers and Mixed-Use Properties. The accounting policies of the segments are the same as those described in the summary of significant accounting policies (see Note 2). The Company evaluates performance based upon income and cash flows from real estate for the combined properties in each segment. All of our properties within each segment generate similar types of revenues and expenses related to tenant rent, reimbursements and operating expenses. Although services are provided to a range of tenants, the types of services provided to them are similar within each segment. The properties in each portfolio have similar economic characteristics and the nature of the products and services provided to our tenants and the method to distribute such services are consistent throughout the portfolio. Certain reclassifications have been made to prior year information to conform to the 2019 presentation. SAUL CENTERS, INC. Notes to Consolidated Financial Statements (In thousands) Shopping Mixed-Use Corporate Consolidated As of or for the year ended December 31, 2019 Centers Properties and Other Totals Real estate rental operations: Revenue $ 167,888 $ 63,637 $ — $ 231,525 Expenses (36,119 ) (21,814 ) — (57,933 ) Income from real estate 131,769 41,823 — 173,592 Interest expense, net and amortization of deferred debt costs — — (41,834 ) (41,834 ) General and administrative — — (20,793 ) (20,793 ) Depreciation and amortization of deferred leasing costs (29,112 ) (17,221 ) — (46,333 ) Change in fair value of derivatives — — (436 ) (436 ) Net income (loss) $ 102,657 $ 24,602 $ (63,063 ) $ 64,196 Capital investment $ 33,968 $ 101,695 $ — $ 135,663 Total assets $ 980,096 $ 625,183 $ 13,061 $ 1,618,340 As of or for the year ended December 31, 2018 Real estate rental operations: Revenue $ 164,344 $ 62,875 $ — $ 227,219 Expenses (34,643 ) (20,935 ) — (55,578 ) Income from real estate 129,701 41,940 — 171,641 Interest expense, net and amortization of deferred debt costs — — (44,768 ) (44,768 ) General and administrative — — (18,459 ) (18,459 ) Depreciation and amortization of deferred leasing costs (29,251 ) (16,610 ) — (45,861 ) Change in fair value of derivatives — — (3 ) (3 ) Gain on sale of property 509 — — 509 Net income (loss) $ 100,959 $ 25,330 $ (63,230 ) $ 63,059 Capital investment $ 13,485 $ 115,165 $ — $ 128,650 Total assets $ 971,321 $ 537,500 $ 18,668 $ 1,527,489 As of or for the year ended December 31, 2017 Real estate rental operations: Revenue $ 165,232 $ 61,067 $ — $ 226,299 Expenses (34,054 ) (20,632 ) — (54,686 ) Income from real estate 131,178 40,435 — 171,613 Interest expense, net and amortization of deferred debt costs — — (47,145 ) (47,145 ) General and administrative — — (18,176 ) (18,176 ) Depreciation and amortization of deferred leasing costs (29,977 ) (15,717 ) — (45,694 ) Change in fair value of derivatives — — 70 70 Net income (loss) $ 101,201 $ 24,718 $ (65,251 ) $ 60,668 Capital investment $ 90,896 $ 29,098 $ — $ 119,994 Total assets $ 974,061 $ 438,283 $ 10,108 $ 1,422,452

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2019
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events The Company has reviewed operating activities for the period subsequent to December 31, 2019 and prior to the date that financial statements are issued, February 27, 2020 , and determined there are no subsequent events that are required to be disclosed.

Real Estate and Accumulated Dep

Real Estate and Accumulated Depreciation	12 Months Ended
	Dec. 31, 2019
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation Disclosure [Abstract]
Real estate and accumulated depreciation	SAUL CENTERS, INC. Real Estate and Accumulated Depreciation December 31, 2019 (Dollars in Thousands) Costs Buildings Capitalized Basis at Close of Period and Initial Basis Subsequent to Acquisition Land Buildings and Improvements Construction in Progress Total Accumulated Depreciation Book Value Related Debt Date of Construction Date Acquired Improvements Depreciable Lives in Years Shopping Centers Ashbrook Marketplace, Ashburn, VA $ 8,938 $ 16,261 $ 3,066 $ 3,005 $ 19,128 $ 25,199 $ 8 $ 25,191 $ — 2019 5/18 40 Ashburn Village, Ashburn, VA 11,431 20,514 6,764 25,077 104 31,945 14,234 17,711 26,245 1994 & 2000-6 3/94 40 Ashland Square Phase I, Dumfries, VA 1,178 7,508 1,178 5,298 2,210 8,686 2,215 6,471 — 2007, 2013 12/04 20 & 50 Beacon Center, Alexandria, VA 24,161 18,477 22,674 19,946 18 42,638 15,335 27,303 36,206 1960 & 1974 1/72, 11/16 40 & 50 BJ’s Wholesale Club, Alexandria, VA 22,623 — 22,623 — — 22,623 — 22,623 10,323 3/08 — Boca Valley Plaza, Boca Raton, FL 16,720 2,064 5,735 13,049 — 18,784 5,252 13,532 9,234 2/04 40 Boulevard, Fairfax, VA 4,883 4,709 3,687 5,905 — 9,592 3,243 6,349 15,723 1969, 1999 & 2009 4/94 40 Briggs Chaney MarketPlace, Silver Spring, MD 27,037 4,703 9,789 21,951 — 31,740 9,333 22,407 — 4/04 40 Broadlands Village, Ashburn, VA 5,316 34,586 5,300 34,589 13 39,902 12,872 27,030 31,221 2003, 2004 & 2006 3/02 40 & 50 Burtonsville Town Square, Burtonsville, MD 74,212 5,612 28,401 50,915 508 79,824 3,728 76,096 36,975 2010 1/17 20 & 45 Countryside Marketplace, Sterling, VA 28,912 4,143 7,666 25,389 — 33,055 10,518 22,537 — 2/04 40 Cranberry Square, Westminster, MD 31,578 739 6,700 25,617 — 32,317 5,497 26,820 15,917 9/11 40 Cruse MarketPlace, Cumming, GA 12,226 689 3,901 9,014 — 12,915 3,626 9,289 — 3/04 40 Flagship Center, Rockville, MD 160 9 169 — — 169 — 169 — 1972 1/72 — French Market, Oklahoma City, OK 5,781 14,269 1,118 18,929 3 20,050 12,490 7,560 — 1972 & 1998 3/74 50 Germantown, Germantown, MD 2,034 567 2,034 567 — 2,601 409 2,192 — 1990 8/93 40 The Glen, Woodbridge, VA 12,918 8,351 5,300 15,942 27 21,269 10,138 11,131 22,448 1993 & 2005 6/94 40 Great Falls Center, Great Falls, VA 41,750 3,203 14,766 30,187 — 44,953 9,497 35,456 10,774 3/08 40 Hampshire Langley, Takoma, MD 3,159 3,549 1,856 4,635 217 6,708 3,908 2,800 14,810 1960 1/72 40 Hunt Club Corners, Apopka, FL 12,584 4,409 4,822 12,171 — 16,993 4,788 12,205 5,300 6/06, 12/12 40 Jamestown Place, Altamonte Springs, FL 14,055 1,950 4,455 11,550 — 16,005 4,291 11,714 6,539 11/05 40 Kentlands Square I, Gaithersburg, MD 14,379 840 5,006 9,711 502 15,219 4,220 10,999 — 2002 9/02 40 Kentlands Square II, Gaithersburg, MD 76,723 2,733 22,800 56,270 386 79,456 12,147 67,309 33,952 9/11, 9/13 40 Kentlands Place, Gaithersburg, MD 1,425 7,373 1,425 7,373 — 8,798 4,241 4,557 — 2005 1/04 50 Lansdowne Town Center, Leesburg, VA 6,545 43,003 6,546 37,843 5,159 49,548 16,291 33,257 30,719 2006 11/02 50 Leesburg Pike Plaza, Baileys Crossroads, VA 2,418 6,292 1,132 7,578 — 8,710 6,159 2,551 14,414 1965 2/66 40 Lumberton Plaza, Lumberton, NJ 4,400 11,612 950 15,041 21 16,012 13,379 2,633 — 1975 12/75 40 Metro Pike Center, Rockville, MD 33,123 4,605 26,064 7,729 3,935 37,728 1,822 35,906 — 12/10 40 Shops at Monocacy, Frederick, MD 9,541 13,994 9,260 14,275 — 23,535 6,338 17,197 28,500 2004 11/03 50 Northrock, Warrenton, VA 12,686 15,429 12,686 15,423 6 28,115 4,907 23,208 14,085 2009 01/08 50 Olde Forte Village, Ft. Washington, MD 15,933 6,721 5,409 17,245 — 22,654 8,180 14,474 21,702 2004 07/03 40 Olney, Olney, MD 4,963 2,550 3,079 4,434 — 7,513 3,358 4,155 11,952 1972 11/75 40 Orchard Park, Dunwoody, GA 19,377 1,461 7,751 13,087 — 20,838 4,053 16,785 9,441 7/07 40 Palm Springs Center, Altamonte Springs, FL 18,365 2,007 5,739 14,633 — 20,372 5,593 14,779 7,262 3/05 40 Ravenwood, Baltimore, MD 1,245 4,256 703 4,798 — 5,501 3,308 2,193 13,606 1959 & 2006 1/72 40 11503 Rockville Pike/5541 Nicholson Lane, Rockville, MD 26,561 24 22,113 4,472 — 26,585 1,032 25,553 — 10/10 40 1500/1580/1582/1584 Rockville Pike, Rockville, MD 51,149 2,714 43,863 7,490 2,510 53,863 6,439 47,424 — 12/12, 1/14, 4/14, 12/14 5, 10, 5, 4 Seabreeze Plaza, Palm Harbor, FL 24,526 2,502 8,665 18,363 — 27,028 6,746 20,282 15,019 11/05 40 Market Place at Sea Colony, Bethany Beach, DE 2,920 246 1,147 2,019 — 3,166 615 2,551 — 3/08 40 Seven Corners, Falls Church, VA 4,848 44,612 4,913 44,522 25 49,460 30,937 18,523 60,677 1956 & 1997 7/73 40 Severna Park Marketplace, Severna Park, MD 63,254 526 12,700 51,080 — 63,780 10,544 53,236 29,710 9/11 40 Shops at Fairfax, Fairfax, VA 2,708 9,971 992 11,687 — 12,679 8,676 4,003 10,482 1975 & 1999 6/75 50 Smallwood Village Center, Waldorf, MD 17,819 8,332 6,402 19,743 6 26,151 8,903 17,248 — 1/06 40 Southdale, Glen Burnie, MD 18,895 25,100 15,254 28,740 1 43,995 22,440 21,555 — 1962 & 1986 1/72 40 Southside Plaza, Richmond, VA 6,728 11,338 1,878 16,188 — 18,066 12,798 5,268 — 1958 1/72 40 South Dekalb Plaza, Atlanta, GA 2,474 4,449 703 6,220 — 6,923 5,088 1,835 — 1970 2/76 40 Thruway, Winston-Salem, NC 7,848 26,336 7,693 26,447 44 34,184 18,682 15,502 — 1955 & 1965 5/72 40 Village Center, Centreville, VA 16,502 2,636 7,851 11,287 — 19,138 7,380 11,758 12,555 1990 8/93 40 Westview Village, Frederick, MD 6,047 25,225 6,047 25,216 9 31,272 9,483 21,789 — 2009 11/07, 02/15 50 White Oak, Silver Spring, MD 6,277 5,771 4,649 7,212 187 12,048 6,169 5,879 22,475 1958 & 1967 1/72 40 Other Buildings / Improvements — 182 — 182 — 182 72 110 — Total Shopping Centers 841,335 449,152 415,424 840,044 35,019 1,290,487 381,382 909,105 578,266 Mixed-Use Properties Avenel Business Park, Gaithersburg, MD 21,459 32,976 3,756 50,679 — 54,435 39,261 15,174 26,260 1981-2000 12/84 35 & 40 Clarendon Center, Arlington, VA (1) 12,753 186,210 16,287 182,676 — 198,963 46,856 152,107 98,611 2010 7/73, 1/96 & 4/02 50 Park Van Ness, Washington, DC 2,242 91,699 2,242 91,699 — 93,941 10,757 83,184 68,095 2016 7/73 & 2/11 50 601 Pennsylvania Ave., Washington, DC 5,479 69,129 5,667 68,941 — 74,608 57,038 17,570 — 1986 7/73 35 Washington Square, Alexandria, VA 2,034 57,102 544 58,592 — 59,136 28,180 30,956 56,990 2000 7/73 50 Total Mixed-Use Properties 43,967 437,116 28,496 452,587 — 481,083 182,092 298,991 249,956 Development Land Ashland Square Phase II, Manassas, VA 5,292 2,280 7,028 — 544 7,572 — 7,572 — 12/04 New Market, New Market, MD 2,088 286 2,374 — — 2,374 — 2,374 — 9/05 The Waycroft, Arlington, VA 52,067 203,376 — — 255,443 255,443 — 255,443 110,199 — 8/14-8/16 7316 Wisconsin Avenue, Bethesda, MD 39,641 4,997 — — 44,638 44,638 — 44,638 — 1969 9/18 & 12/18 Total Development Land 99,088 210,939 9,402 — 300,625 310,027 — 310,027 110,199 Total $ 984,390 $ 1,097,207 $ 453,322 $ 1,292,631 $ 335,644 $ 2,081,597 $ 563,474 $ 1,518,123 $ 938,421 (1) Includes the North and South Blocks and Residential Depreciation and amortization related to the real estate investments reflected in the statements of operations is calculated over the estimated useful lives of the assets as follows: Base building Generally 35 - 50 years or a shorter period if management determines that the building has a shorter useful life. Building components Up to 20 years Tenant improvements The shorter of the term of the lease or the useful life of the improvements The aggregate remaining net basis of the real estate investments for federal income tax purposes was approximately $1.33 billion at December 31, 2019 . Depreciation and amortization are provided on the declining balance and straight-line methods over the estimated useful lives of the assets. The changes in total real estate investments and related accumulated depreciation for each of the years in the three year period ended December 31, 2019 are summarized as follows: (In thousands) 2019 2018 2017 Total real estate investments: Balance, beginning of year $ 1,948,165 $ 1,803,200 $ 1,700,813 Acquisitions — 48,579 77,258 Improvements 135,966 98,917 42,640 Retirements (2,534 ) (2,531 ) (17,511 ) Balance, end of year $ 2,081,597 $ 1,948,165 $ 1,803,200 Total accumulated depreciation: Balance, beginning of year $ 525,518 $ 488,166 $ 458,279 Depreciation expense 40,490 39,768 40,197 Retirements (2,534 ) (2,416 ) (10,310 ) Balance, end of year $ 563,474 $ 525,518 $ 488,166

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make certain estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expenses during the reporting period. The most significant estimates and assumptions relate to impairment of real estate properties. Actual results could differ from those estimates.
Real Estate Investment Properties	Real Estate Investment Properties Real estate investment properties are stated at historic cost less depreciation. Although the Company intends to own its real estate investment properties over a long term, from time to time it will evaluate its market position, market conditions, and other factors and may elect to sell properties that do not conform to the Company’s investment profile. Management believes that the Company’s real estate assets have generally appreciated in value since their acquisition or development and, accordingly, the aggregate current value exceeds their aggregate net book value and also exceeds the value of the Company’s liabilities as reported in the financial statements. Because the financial statements are prepared in conformity with GAAP, they do not report the current value of the Company’s real estate investment properties. If there is an event or change in circumstance that indicates a potential impairment in the value of a real estate investment property, the Company prepares an analysis to determine whether the carrying value of the real estate investment property exceeds its estimated fair value. The Company considers both quantitative and qualitative factors including recurring operating losses, significant decreases in occupancy, and significant adverse changes in legal factors and business climate. If impairment indicators are present, the Company compares the projected cash flows of the property over its remaining useful life, on an undiscounted basis, to the carrying value of that property. The Company assesses its undiscounted projected cash flows based upon estimated capitalization rates, historic operating results and market conditions that may affect the property. If the carrying value is greater than the undiscounted projected cash flows, the Company would recognize an impairment loss equivalent to an amount required to adjust the carrying amount to its then estimated fair value. The fair value of any property is sensitive to the actual results of any of the aforementioned estimated factors, either individually or taken as a whole. Should the actual results differ from management’s projections, the valuation could be negatively or positively affected. The Company did not recognize an impairment loss on any of its real estate in 2019 , 2018 , or 2017 . Depreciation is calculated using the straight-line method and estimated useful lives of generally between 35 and 50 years for base buildings, or a shorter period if management determines that the building has a shorter useful life, and up to 20 years for certain other improvements that extend the useful lives. Leasehold improvements expenditures are capitalized when certain criteria are met, including when the Company supervises construction and will own the improvements. Tenant improvements are amortized, over the shorter of the lives of the related leases or the useful life of the improvement, using the straight-line method. Depreciation expense, which is included in Depreciation and amortization of deferred leasing costs in the Consolidated Statements of Operations, for the years ended December 31, 2019 , 2018 , and 2017 , was $40.5 million , $39.8 million , and $40.2 million , respectively. Repairs and maintenance expense totaled $12.5 million , $11.9 million , and $11.6 million for 2019 , 2018 , and 2017 , respectively, and is included in property operating expenses in the accompanying consolidated financial statements.
Assets Held for Sale	Assets Held for Sale The Company considers properties to be assets held for sale when all of the following criteria are met: • management commits to a plan to sell a property; • it is unlikely that the disposal plan will be significantly modified or discontinued; • the property is available for immediate sale in its present condition; • actions required to complete the sale of the property have been initiated; • sale of the property is probable and the Company expects the completed sale will occur within one year; and • the property is actively being marketed for sale at a price that is reasonable given its current market value.
Revenue Recognition	Revenue Recognition Rental and interest income are accrued as earned. Recognition of rental income commences when control of the space has been given to the tenant. When rental payments due under leases vary from a straight-line basis because of free rent periods or stepped increases, income is recognized on a straight-line basis. Expense recoveries represent a portion of property operating expenses billed to the tenants, including common area maintenance, real estate taxes and other recoverable costs. Expense recoveries are recognized in the period in which the expenses are incurred. Rental income based on a tenant’s revenue (“percentage rent”) is accrued when a tenant reports sales that exceed a specified breakpoint, pursuant to the terms of their respective leases.
Accounts Receivable, Accrued Income, and Allowance for Doubtful Accounts	Accounts Receivable, Accrued Income, and Allowance for Doubtful Accounts Accounts receivable primarily represent amounts currently due from tenants in accordance with the terms of their respective leases. Lease related receivables are reduced for credit losses. Such losses are recognized as a reduction of rental revenue in the consolidated statements of operations. Receivables are reviewed monthly and reserves are established with a charge to current period operations when, in the opinion of management, collection of the receivable is doubtful. Accounts receivable in the accompanying consolidated financial statements are shown net of an allowance for doubtful accounts of $0.4 million and $0.6 million , at December 31, 2019 and 2018 , respectively.
Deferred Leasing Costs	Deferred Leasing Costs
Cash and Cash Equivalents	Cash and Cash Equivalents Cash and cash equivalents include short-term investments. Short-term investments include money market accounts and other investments which generally mature within three months, measured from the acquisition date, and/or are readily convertible to cash. Substantially all of the Company’s cash balances at December 31, 2019 are held in non-interest bearing accounts at various banks. From time to time the Company may maintain deposits with financial institutions in amounts in excess of federally insured limits. The Company has not experienced any losses on such deposits and believes it is not exposed to any significant credit risk on those deposits.
Deferred Income	Deferred Income Deferred income consists of payments received from tenants prior to the time they are earned and recognized by the Company as revenue, including tenant prepayment of rent for future periods, real estate taxes when the taxing jurisdiction has a fiscal year differing from the calendar year reimbursements specified in the lease agreement and tenant construction work provided by the Company. In addition, deferred income includes the fair value of certain below market leases.
Derivative Financial Instruments	Derivative Financial Instruments The Company may, when appropriate, employ derivative instruments, such as interest-rate swaps, to mitigate the risk of interest rate fluctuations. The Company does not enter into derivative or other financial instruments for trading or speculative purposes. Derivative financial instruments are carried at fair value as either assets or liabilities on the consolidated balance sheets. For those derivative instruments that qualify, the Company may designate the hedging instrument, based upon the exposure being hedged, as a fair value hedge or a cash flow hedge. Derivative instruments that are designated as a hedge are evaluated to ensure they continue to qualify for hedge accounting. The effective portion of any gain or loss on the hedge instruments is reported as a component of accumulated other comprehensive income (loss) and recognized in earnings within the same line item associated with the forecasted transaction in the same period or periods during which the hedged transaction affects earnings. Any ineffective portion of the change in fair value of a derivative instrument is immediately recognized in earnings. For derivative instruments that do not meet the criteria for hedge accounting, or that qualify and are not designated, changes in fair value are immediately recognized in earnings.
Income Taxes	Income Taxes The Company made an election to be treated, and intends to continue operating so as to qualify, as a REIT under the Code, commencing with its taxable year ended December 31, 1993 . A REIT generally will not be subject to federal income taxation, provided that distributions to its stockholders equal or exceed its REIT taxable income and complies with certain other requirements. Therefore, no provision has been made for federal income taxes in the accompanying consolidated financial statements. As of December 31, 2019
Legal Contingencies	Legal Contingencies The Company is subject to various legal proceedings and claims that arise in the ordinary course of business, which are generally covered by insurance. Upon determination that a loss is probable to occur and can be reasonably estimated, the estimated amount of the loss is recorded in the financial statements.
Recently Issued Accounting Standards	Recently Issued Accounting Standards In February 2016, the Financial Accounting Standards Board (‘‘FASB’’) issued Accounting Standards Update (‘‘ASU’’) 2016-02, ‘‘Leases’’ (“ASU 2016-02”). ASU 2016-02 amends the existing accounting standards for lease accounting, including requiring lessees to recognize most leases on their balance sheets and making targeted changes to lessor accounting. ASU 2016-02 is effective for annual periods beginning after December 15, 2018, interim periods within those years, and requires a modified retrospective transition approach for all leases existing at the date of initial application, with an option to use certain practical expedients for those existing leases. Upon adoption of ASU 2016-02 effective January 1, 2019, we elected the practical expedient for all leases with respect to lease identification, lease classification, and initial direct costs. We made a policy election not to separate lease and nonlease components and have accounted for each lease component and the related nonlease components together as a single component. There have been no significant changes to our lessor accounting for operating leases as a result of ASU 2016-02. We lease Shopping Centers and Mixed-Use Properties to lessees in exchange for monthly payments that cover rent, and where applicable, reimbursement for property taxes, insurance, and certain property operating expenses. Our leases were determined to be operating leases and generally range in term from one to 15 years . Some of our leases have termination options and/or extension options. Termination options allow the lessee to terminate the lease prior to the end of the lease term, provided certain conditions are met. Termination options generally require advance notification from the lessee and payment of a termination fee. Termination fees are recognized as revenue over the modified lease term. Extension options are subject to terms and conditions stated in the lease. On January 1, 2019, a right of use asset and corresponding lease liability related to our headquarters lease were recorded in other assets and other liabilities, respectively. The lease expires on February 28, 2022, with one option to renew for an additional five years . The right of use asset and corresponding lease liability totaled $1.6 million and $1.6 million , respectively, at December 31, 2019. In June 2016, the FASB issued ASU 2016-13, "Financial Instruments-Credit Losses" ("ASU 2016-13"). ASU 2016-13 replaces the incurred loss impairment methodology with a methodology that reflects expected credit losses and requires consideration of a broader range of information to support credit loss estimates. ASU 2016-13 is effective for annual periods beginning after December 15, 2019, including interim periods within those years. Management has determined that the adoption of ASU 2016-13 will not have a material impact on our consolidated financial statements and related disclosures because the vast majority of the Company's receivables relate to operating leases which are accounted for under ASC 842. In August 2017, the FASB issued ASU 2017-12, “Derivatives and Hedging” (“ASU 2017-12”). ASU 2017-12 amends financial reporting for hedging activities to better align that reporting with risk management activities. ASU 2017-12 expands and refines hedge accounting for both financial and nonfinancial risk components and aligns the recognition and presentation of the effects of the hedging instrument and the hedged item in the financial statements. Effective with the adoption of ASU 2017-12 on January 1, 2019, changes in the fair value of the Company’s interest rate swap related to changes in the cash flow of the hedged item are reported as a component of interest expense and amortization of deferred debt costs in the Statements of Operations.
Reclassifications	Reclassifications Certain reclassifications have been made to prior years to conform to the presentation used for year ended December 31, 2019

Real Estate (Tables)

Real Estate (Tables)	12 Months Ended
	Dec. 31, 2019
Real Estate [Abstract]
Schedule of Construction in Progress	The following table shows the components of construction in progress. December 31, (in thousands) 2019 2018 The Waycroft $ 255,443 $ 162,176 7316 Wisconsin Avenue 44,638 — Ashbrook Marketplace 19,128 11,124 Other 16,435 12,672 Total $ 335,644 $ 185,972
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed	The purchase price was allocated to assets acquired and liabilities assumed based on their relative fair values as shown in the following table. (in thousands) Ashbrook Marketplace 7316 Wisconsin Avenue Total Land $ 8,776 $ 38,662 $ 47,438 Buildings — 979 979 In-place Leases — 886 886 Above Market Rent — 168 168 Below Market Rent — (21 ) (21 ) Total Purchase Price $ 8,776 $ 40,674 $ 49,450
Amortization of intangible assets and deferred income related to in place leases	As of December 31, 2019 , scheduled amortization of intangible assets and deferred income related to in place leases is as follows: (In thousands) Lease acquisition costs Above market leases Below market leases 2020 $ 708 $ 43 $ 1,434 2021 535 33 1,409 2022 383 33 1,306 2023 317 33 1,297 2024 198 33 878 Thereafter 996 343 3,853 Total $ 3,137 $ 518 $ 10,177

Mortgage Notes Payable, Revol_2

Mortgage Notes Payable, Revolving Credit Facility, Interest Expense and Amortization of Deferred Debt Costs (Tables)	12 Months Ended
	Dec. 31, 2019
Debt Disclosure [Abstract]
Scheduled maturities of all debt, including scheduled principal amortization	As of December 31, 2019 , the scheduled maturities of all debt including scheduled principal amortization for years ended December 31 are as follows: (in thousands) Balloon Payments Scheduled Principal Amortization Total 2020 $ 16,074 $ 28,421 $ 44,495 2021 11,012 29,025 40,037 2022 124,002 (a) 29,645 153,647 2023 84,225 30,065 114,290 2024 66,649 28,697 95,346 Thereafter 527,297 125,809 653,106 Principal amount $ 829,259 $ 271,662 1,100,921 Unamortized deferred debt costs 9,733 Net $ 1,091,188 (a) Includes $87.5 million outstanding under the revolving facility.
Components of interest expense	The components of interest expense are set forth below. (in thousands) Year ended December 31, 2019 2018 2017 Interest incurred $ 52,044 $ 49,652 $ 49,322 Amortization of deferred debt costs 1,518 1,610 1,392 Capitalized interest (11,480 ) (6,222 ) (3,489 ) Interest expense 42,082 45,040 47,225 Less: Interest income 248 272 80 Interest expense, net and amortization of deferred debt costs $ 41,834 $ 44,768 $ 47,145

Lease Agreements (Tables)

Lease Agreements (Tables)	12 Months Ended
	Dec. 31, 2019
Leases [Abstract]
Future contractual payments under noncancelable leases	Future contractual payments under noncancelable leases for years ended December 31 (which exclude the effect of straight-line rents), are as follows: (in thousands) 2020 $ 166,227 2021 149,949 2022 126,101 2023 104,489 2024 75,172 Thereafter 260,141 $ 882,079

Equity and Noncontrolling Int_2

Equity and Noncontrolling Interest Equity Weighted Average Shares Outstanding (Tables)	12 Months Ended
	Dec. 31, 2019
Noncontrolling Interest [Abstract]
Schedule of Weighted Average Number of Shares	Per share data for net income (basic and diluted) is computed using weighted average shares of common stock. Convertible limited partnership units and employee stock options are the Company’s potentially dilutive securities. For all periods presented, the convertible limited partnership units are anti-dilutive. The treasury stock method was used to measure the effect of the dilution. December 31, (Shares in thousands) 2019 2018 2017 Weighted average common shares outstanding - Basic 23,009 22,383 21,901 Effect of dilutive options 44 42 107 Weighted average common shares outstanding - Diluted 23,053 22,425 22,008 Average share price $ 53.41 $ 52.50 $ 61.63 Non-dilutive options 633 492 — Years non-dilutive options were issued 2016, 2017 and 2019 2015, 2016 and 2017

Stock Option Plan (Tables)

Stock Option Plan (Tables)	12 Months Ended
	Dec. 31, 2019
Share-based Payment Arrangement [Abstract]
Stock Options Issued	Directors Officers Grant date May 5, 2017 May 11, 2018 May 3, 2019 May 5, 2017 May 11, 2018 May 3, 2019 Exercise price $ 59.41 $ 49.46 $ 55.71 $ 59.41 $ 49.46 $ 55.71 Volatility 0.173 0.192 0.236 0.170 0.177 0.206 Expected life (years) 5.0 5.0 5.0 7.0 7.0 7.0 Assumed yield 3.45 % 3.70 % 3.75 % 3.50 % 3.75 % 3.80 % Risk-free rate 1.89 % 2.84 % 2.33 % 2.17 % 2.94 % 2.43 %
Summary of Option Activity	The table below summarizes the option activity for the years 2019 , 2018 , and 2017 : 2019 2018 2017 Shares Weighted Shares Weighted Shares Weighted Outstanding at January 1 1,114,169 $ 52.40 913,320 $ 52.80 833,630 $ 49.92 Granted 260,000 55.71 245,000 49.46 232,500 59.41 Exercised (57,055 ) 44.53 (39,151 ) 42.98 (149,060 ) 46.97 Expired/Forfeited (7,500 ) 56.07 (5,000 ) 54.78 (3,750 ) 53.73 Outstanding December 31 1,309,614 53.38 1,114,169 52.40 913,320 52.80 Exercisable at December 31 763,614 52.43 600,919 50.93 430,945 48.94

Distributions (Tables)

Distributions (Tables)	12 Months Ended
	Dec. 31, 2019
Equity [Abstract]
Summary of distributions paid including activity in plan as well as limited partnership units issued from reinvestment of unit distributions	The following summarizes distributions paid during the years ended December 31, 2019 , 2018 , and 2017 , and includes activity in the Plan as well as limited partnership units issued from the reinvestment of unit distributions: Total Distributions to Dividend Reinvestments (Dollars in thousands, except per share amounts) Preferred Common Limited Common Discounted Limited Partnership Units Issued Average Unit Price Distributions during 2019 4th Quarter $ 3,531 $ 12,251 $ 4,173 104,558 $ 52.84 13,747 $ 53.73 3rd Quarter 2,953 12,195 4,166 105,753 53.66 13,406 54.56 2nd Quarter 2,953 12,116 4,155 99,804 51.38 20,041 51.99 1st Quarter 2,953 12,006 4,148 120,347 51.28 13,742 52.16 Total 2019 $ 12,390 $ 48,568 $ 16,642 430,462 60,936 Distributions during 2018 4th Quarter $ 2,953 $ 11,706 $ 4,062 216,476 $ 49.34 13,867 $ 50.20 3rd Quarter 2,953 11,590 4,055 201,500 51.68 13,107 52.60 2nd Quarter 2,672 11,545 3,942 85,202 47.54 42,422 47.83 1st Quarter 3,824 11,465 3,922 69,750 52.71 38,037 53.03 Total 2018 $ 12,402 $ 46,306 $ 15,981 572,928 107,433 Distributions during 2017 4th Quarter $ 3,094 $ 11,221 $ 3,838 82,991 $ 59.33 15,596 $ 60.08 3rd Quarter 3,094 11,160 3,830 85,731 57.40 16,021 58.13 2nd Quarter 3,094 11,119 3,810 51,003 59.64 40,623 59.96 1st Quarter 3,093 11,076 3,790 46,286 61.85 39,111 62.15 Total 2017 $ 12,375 $ 44,576 $ 15,268 266,011 111,351

Interim Results (Unaudited) (Ta

Interim Results (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2019
Quarterly Financial Information Disclosure [Abstract]
Summary of results of operations for quarterly periods	The following summary presents the results of operations of the Company for the quarterly periods of calendar years 2019 and 2018 . (In thousands, except per share amounts) 2019 1st Quarter 2nd Quarter 3rd Quarter 4th Quarter Total revenue $ 59,750 $ 58,141 $ 57,052 $ 56,582 Net Income 17,077 16,750 15,328 15,041 Net income attributable to Saul Centers, Inc. 13,447 13,232 12,226 12,818 Net income available to common stockholders 10,494 10,279 9,016 6,464 Net income available to common stockholders per diluted share 0.46 0.45 0.39 0.27 (In thousands, except per share amounts) 2018 1st Quarter 2nd Quarter 3rd Quarter 4th Quarter Total revenue $ 56,109 $ 56,081 $ 56,910 $ 58,119 Net Income 14,946 15,902 16,702 15,509 Net income attributable to Saul Centers, Inc. 12,587 12,543 13,155 12,269 Net income available to common stockholders 6,856 9,590 10,202 9,316 Net income available to common stockholders per diluted share 0.31 0.43 0.45 0.41

Business Segments (Tables)

Business Segments (Tables)	12 Months Ended
	Dec. 31, 2019
Segment Reporting [Abstract]
Business Segments	SAUL CENTERS, INC. Notes to Consolidated Financial Statements (In thousands) Shopping Mixed-Use Corporate Consolidated As of or for the year ended December 31, 2019 Centers Properties and Other Totals Real estate rental operations: Revenue $ 167,888 $ 63,637 $ — $ 231,525 Expenses (36,119 ) (21,814 ) — (57,933 ) Income from real estate 131,769 41,823 — 173,592 Interest expense, net and amortization of deferred debt costs — — (41,834 ) (41,834 ) General and administrative — — (20,793 ) (20,793 ) Depreciation and amortization of deferred leasing costs (29,112 ) (17,221 ) — (46,333 ) Change in fair value of derivatives — — (436 ) (436 ) Net income (loss) $ 102,657 $ 24,602 $ (63,063 ) $ 64,196 Capital investment $ 33,968 $ 101,695 $ — $ 135,663 Total assets $ 980,096 $ 625,183 $ 13,061 $ 1,618,340 As of or for the year ended December 31, 2018 Real estate rental operations: Revenue $ 164,344 $ 62,875 $ — $ 227,219 Expenses (34,643 ) (20,935 ) — (55,578 ) Income from real estate 129,701 41,940 — 171,641 Interest expense, net and amortization of deferred debt costs — — (44,768 ) (44,768 ) General and administrative — — (18,459 ) (18,459 ) Depreciation and amortization of deferred leasing costs (29,251 ) (16,610 ) — (45,861 ) Change in fair value of derivatives — — (3 ) (3 ) Gain on sale of property 509 — — 509 Net income (loss) $ 100,959 $ 25,330 $ (63,230 ) $ 63,059 Capital investment $ 13,485 $ 115,165 $ — $ 128,650 Total assets $ 971,321 $ 537,500 $ 18,668 $ 1,527,489 As of or for the year ended December 31, 2017 Real estate rental operations: Revenue $ 165,232 $ 61,067 $ — $ 226,299 Expenses (34,054 ) (20,632 ) — (54,686 ) Income from real estate 131,178 40,435 — 171,613 Interest expense, net and amortization of deferred debt costs — — (47,145 ) (47,145 ) General and administrative — — (18,176 ) (18,176 ) Depreciation and amortization of deferred leasing costs (29,977 ) (15,717 ) — (45,694 ) Change in fair value of derivatives — — 70 70 Net income (loss) $ 101,201 $ 24,718 $ (65,251 ) $ 60,668 Capital investment $ 90,896 $ 29,098 $ — $ 119,994 Total assets $ 974,061 $ 438,283 $ 10,108 $ 1,422,452

Organization, Basis of Presen_2

Organization, Basis of Presentation - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2019tenantpartnershipstoreproperty
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Distribution of REIT taxable income (excluding net capital gains) to its stockholders	90.00%
Number of partnerships | partnership	2
Number of stores | store	33
Shopping Centers
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Number of real estate properties	50
Mixed-Use Properties
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Number of real estate properties	6
Non-operating Development Properties
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Number of real estate properties	4
Revenue Benchmark
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Number of tenants | tenant	1
Percentage of total revenue	2.50%
Revenue Benchmark | Giant Food
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Number of stores | store	10
Percentage of total revenue	4.70%
Saul Holdings Limited Partnership
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Percentage of ownership in operating partnership	74.60%

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Jan. 01, 2019lease_option
Significant Accounting Policies [Line Items]
Depreciation and amortization of deferred leasing costs	$ 40,490,000	$ 39,768,000	$ 40,197,000
Repairs and maintenance expense	12,500,000	11,900,000	11,600,000
Allowance for doubtful accounts receivables	400,000	600,000
Accounts receivable, net representing rental income accrued	42,100,000	43,300,000
Allowance for doubtful accounts receivables representing rental income accrued	30,000	58,500
Deferred leasing costs, net	24,083,000	28,083,000
Accumulated amortization deferred leasing cost	(41,600,000)	(37,700,000)
Amortization expense deferred leasing cost	5,800,000	6,100,000	5,500,000
Accrued penalties and interest	0	0	$ 0
Tax basis of the company's real estate investments	1,330,000,000	$ 1,350,000,000
Right-of-use asset	1,600,000
Operating lease liability	$ 1,600,000
Minimum
Significant Accounting Policies [Line Items]
Operating lease term of contract				1 year
Minimum | Building
Significant Accounting Policies [Line Items]
Estimated useful life	35 years
Maximum
Significant Accounting Policies [Line Items]
Operating lease term of contract				15 years
Maximum | Building
Significant Accounting Policies [Line Items]
Estimated useful life	50 years
Maximum | Building Improvements
Significant Accounting Policies [Line Items]
Estimated useful life	20 years
Corporate Headquarters
Significant Accounting Policies [Line Items]
Number of options to extend lease | lease_option				1
Lease renewal term				5 years

Real Estate - Schedule of Const

Real Estate - Schedule of Construction in Progress (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Sep. 01, 2019	Dec. 31, 2018
Real Estate [Line Items]
Development in process	$ 335,644		$ 185,972
The Waycroft
Real Estate [Line Items]
Development in process	255,443		162,176
7316 Wisconsin Avenue
Real Estate [Line Items]
Development in process	44,638	$ 42,600	0
Ashbrook Marketplace
Real Estate [Line Items]
Development in process	19,128		11,124
Other
Real Estate [Line Items]
Development in process	$ 16,435		$ 12,672

Real Estate - Additional Inform

Real Estate - Additional Information (Detail)	May 09, 2018shares	Dec. 31, 2018USD ($)	Sep. 30, 2018USD ($)	May 31, 2018USD ($)ashares	Mar. 31, 2017USD ($)	Jan. 31, 2017USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)property	Sep. 01, 2019USD ($)tenant	Dec. 31, 2016USD ($)
Real Estate Properties [Line Items]
Rent expense								$ 779,800	$ 774,700
Acquisition costs				$ 200,000
Development in process		$ 185,972,000					$ 335,644,000	185,972,000
Total purchase price		1,948,165,000					2,081,597,000	1,948,165,000	$ 1,803,200,000		$ 1,700,813,000
Number of properties acquired | property									1
Purchase price allocated to land							453,322,000
Purchase price allocated to buildings							1,292,631,000
Below market lease, carrying amount		24,800,000					24,100,000	24,800,000
Below market lease, accumulated amortization		13,100,000					13,900,000	13,100,000
Accretion income, intangible liabilities							1,500,000	1,700,000	$ 1,700,000
Lease acquisition costs
Real Estate Properties [Line Items]
Intangible assets gross carrying amount		12,500,000					11,700,000	12,500,000
Intangible assets, accumulated amortization		8,100,000					8,500,000	8,100,000
Amortization expense							$ 900,000	1,300,000	1,100,000
Weighted-average amortization period							4 years 6 months
Above Market Rent
Real Estate Properties [Line Items]
Intangible assets gross carrying amount		800,000					$ 600,000	800,000
Intangible assets, accumulated amortization		143,900					108,300	143,900
Amortization expense							$ 109,600	110,500	31,600
Weighted-average amortization period							7 years 7 months 6 days
Below Market Rent
Real Estate Properties [Line Items]
Weighted-average amortization period							5 years 3 months 18 days
Burtonsville Town Square
Real Estate Properties [Line Items]
Payments to acquire real estate						$ 76,400,000			76,400,000
Purchase price allocated to land									28,400,000
Purchase price allocated to buildings									45,800,000
Burtonsville Town Square | In-place Leases
Real Estate Properties [Line Items]
Intangible assets									2,200,000
Burtonsville Town Square | Above Market Rent
Real Estate Properties [Line Items]
Intangible assets									600,000
Burtonsville Town Square | Below Market Rent
Real Estate Properties [Line Items]
Intangible assets									$ 600,000
Olney
Real Estate Properties [Line Items]
Payments to acquire real estate					$ 3,100,000
Rent expense					$ 56,000
2018 Acquisitions
Real Estate Properties [Line Items]
Total purchase price		49,450,000						49,450,000
Purchase price allocated to land		47,438,000						47,438,000
Purchase price allocated to buildings		979,000						979,000
2018 Acquisitions | In-place Leases
Real Estate Properties [Line Items]
Intangible assets		886,000						886,000
2018 Acquisitions | Above Market Rent
Real Estate Properties [Line Items]
Intangible assets		168,000						168,000
2018 Acquisitions | Below Market Rent
Real Estate Properties [Line Items]
Intangible assets		21,000						21,000
Ashbrook Marketplace
Real Estate Properties [Line Items]
Limited partnership units issued				$ 8,800,000				8,776,000
Development in process		11,124,000					$ 19,128,000	11,124,000
7316 Wisconsin Avenue
Real Estate Properties [Line Items]
Payments to acquire real estate			$ 35,500,000
Acquisition costs			$ 700,000
Number of tenants | tenant										2
Development in process		0					$ 44,638,000	$ 0		$ 42,600,000
Parcel Adjacent to 7316 Wisconsin Avenue
Real Estate Properties [Line Items]
Payments to acquire real estate		$ 4,500,000
BF Saul Real Estate Investment Trust | Ashbrook Marketplace
Real Estate Properties [Line Items]
Limited partnership units issued (in shares) | shares	176,680			176,680
Area of land | a				13.7

Real Estate - Allocation of Pur

Real Estate - Allocation of Purchase Prices to Acquired Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Real Estate Properties [Line Items]
Land	$ 453,322
Buildings	1,292,631
Total Purchase Price	$ 2,081,597	$ 1,948,165	$ 1,803,200	$ 1,700,813
Ashbrook Marketplace
Real Estate Properties [Line Items]
Land		8,776
Buildings		0
Total Purchase Price		8,776
Ashbrook Marketplace | In-place Leases
Real Estate Properties [Line Items]
Intangible assets		0
Ashbrook Marketplace | Above Market Rent
Real Estate Properties [Line Items]
Intangible assets		0
Ashbrook Marketplace | Below Market Rent
Real Estate Properties [Line Items]
Intangible assets		0
7316 Wisconsin Avenue
Real Estate Properties [Line Items]
Land		38,662
Buildings		979
Total Purchase Price		40,674
7316 Wisconsin Avenue | In-place Leases
Real Estate Properties [Line Items]
Intangible assets		(886)
7316 Wisconsin Avenue | Above Market Rent
Real Estate Properties [Line Items]
Intangible assets		(168)
7316 Wisconsin Avenue | Below Market Rent
Real Estate Properties [Line Items]
Intangible assets		(21)
2018 Acquisitions
Real Estate Properties [Line Items]
Land		47,438
Buildings		979
Total Purchase Price		49,450
2018 Acquisitions | In-place Leases
Real Estate Properties [Line Items]
Intangible assets		(886)
2018 Acquisitions | Above Market Rent
Real Estate Properties [Line Items]
Intangible assets		(168)
2018 Acquisitions | Below Market Rent
Real Estate Properties [Line Items]
Intangible assets		$ (21)

Real Estate - Amortization of I

Real Estate - Amortization of Intangible Assets and Deferred Income Related to in Place Leases (Detail) $ in Thousands	Dec. 31, 2019USD ($)
Below market leases
2020	$ 1,434
2021	1,409
2022	1,306
2023	1,297
2024	878
Thereafter	3,853
Total	10,177
Lease acquisition costs
Finite-Lived Intangible Assets [Line Items]
2020	708
2021	535
2022	383
2023	317
2024	198
Thereafter	996
Total	3,137
Above market leases
Finite-Lived Intangible Assets [Line Items]
2020	43
2021	33
2022	33
2023	33
2024	33
Thereafter	343
Total	$ 518

Noncontrolling Interests - Ho_2

Noncontrolling Interests - Holders of Convertible Limited Partnership Units in the Operating Partnership - Additional Information (Detail) - shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Noncontrolling Interests
Noncontrolling Interest [Line Items]
Limited partnership units (in shares)	7,886,916
Limited partnership units, conversion ratio	1
Outstanding stock percent that should be acquired for rights to be exercised	39.90%
Limited partnership units convertible to shares of common stock, eligible for conversion (in shares)	925,000
Fully converted partnership units and diluted weighted average shares outstanding (in shares)	30,900,000	30,200,000	29,500,000
Saul Holdings Limited Partnership
Noncontrolling Interest [Line Items]
Percentage of ownership in operating partnership	74.60%
Saul Holdings Limited Partnership | Noncontrolling Interests
Noncontrolling Interest [Line Items]
Percentage of ownership interest of noncontrolling interest	25.40%

Mortgage Notes Payable, Revol_3

Mortgage Notes Payable, Revolving Credit Facility, Interest Expense and Amortization of Deferred Debt Costs - Additional Information (Detail)

Nov. 12, 2019USD ($)

Jan. 10, 2019USD ($)

Dec. 18, 2018USD ($)

Oct. 03, 2018USD ($)

Nov. 20, 2017USD ($)

Aug. 14, 2017USD ($)

Jan. 18, 2017USD ($)

Sep. 30, 2017USD ($)

Dec. 31, 2021USD ($)

Dec. 31, 2019USD ($)

Oct. 01, 2021USD ($)

Oct. 01, 2020USD ($)

Nov. 21, 2019USD ($)

Jun. 03, 2019USD ($)

Jan. 04, 2019USD ($)

Dec. 31, 2018USD ($)

Dec. 31, 2017USD ($)

Sep. 01, 2017USD ($)

Debt Instrument [Line Items]

Outstanding debt

$ 1,100,000,000

Fixed rate mortgages

821,503,000

$ 880,271,000

Variable rate debt

74,691,000

74,591,000

Principal amount

1,100,921,000

1,000,000,000

Debt outstanding with fixed-rate

910,200,000

Debt outstanding with variable-rate

122,000,000

Remaining loan balance

271,662,000

Unamortized deferred debt costs

9,733,000

10,300,000

Accumulated amortization

7,500,000

7,300,000

Capitalization of debt issuance cost

1,000,000

3,200,000

$ 2,600,000

Mortgage Notes Payable

Debt Instrument [Line Items]

Guarantor obligations, maximum exposure

41,000,000

51,000,000

Fixed rate mortgage notes payable

Debt Instrument [Line Items]

Fixed rate mortgages

938,400,000

910,200,000

Fixed rate mortgage notes payable | 3.75% due December 2032 | Washington Square

Debt Instrument [Line Items]

Remaining loan balance

$ 28,100,000

Variable rate loans payable

Debt Instrument [Line Items]

Variable rate debt

162,500,000

New Facility | Line of Credit

Debt Instrument [Line Items]

Line of credit facility, maximum borrowing capacity

$ 400,000,000

Extension in line of credit facility period

1 year

Available borrowing capacity

$ 237,300,000

Outstanding line of credit

87,500,000

Letter of credit available borrowing capacity

185,000

New Facility | Revolving Credit Facility | Line of Credit

Debt Instrument [Line Items]

Line of credit facility, maximum borrowing capacity

$ 325,000,000

Interest rate spread on LIBOR

1.35%

New Facility | Revolving Credit Facility | Term Facility

Debt Instrument [Line Items]

Interest rate spread on LIBOR

1.30%

New Facility | Term Facility | Line of Credit

Debt Instrument [Line Items]

Line of credit facility, maximum borrowing capacity

$ 75,000,000

Park Van Ness Loan

Debt Instrument [Line Items]

Fixed rate mortgages

68,100,000

Guarantor obligations, maximum exposure

6,700,000

Park Van Ness Loan | 4.88% due September 2032

Debt Instrument [Line Items]

Loan required periodic principal and interest payment

$ 413,460

Loan fixed interest rate

4.88%

Amortization schedule

25 years

Balloon payment to be paid

$ 39,600,000

Kentlands Square I | Revolving Credit Facility | 4.41% mortgage maturing 2033

Debt Instrument [Line Items]

Remaining loan balance

$ 6,100,000

Kentlands Square II Bank Loan | Fixed rate mortgage notes payable

Debt Instrument [Line Items]

Guarantor obligations, maximum exposure

8,500,000

Remaining loan balance

34,000,000

Burtonsville Fixed Rate Mortgage | 3.39% due January 2032

Debt Instrument [Line Items]

Loan amount

$ 40,000,000

Loan required periodic principal and interest payment

$ 197,900

Loan term

15 years

Loan fixed interest rate

3.39%

Amortization schedule

25 years

Balloon payment to be paid

$ 20,300,000

Waycroft Construction Loan | 4.67% Construction To Permanent Loan Due 2035

Debt Instrument [Line Items]

Loan amount

$ 157,000,000

Loan fixed interest rate

4.67%

Amortization schedule

25 years

Washington Square 2017 Mortgage | 3.75% due December 2032

Debt Instrument [Line Items]

Loan amount

60,000,000

Loan required periodic principal and interest payment

$ 308,500

Loan term

15 years

Loan fixed interest rate

3.75%

Amortization schedule

25 years

Balloon payment to be paid

$ 31,100,000

Broadlands Village

Debt Instrument [Line Items]

Guarantor obligations, maximum exposure

3,900,000

Remaining loan balance

31,200,000

Broadlands Village | 4.41% mortgage maturing 2033

Debt Instrument [Line Items]

Remaining loan balance

15,200,000

Loan amount

32,000,000

Loan required periodic principal and interest payment

$ 176,200

Loan term

15 years

Loan fixed interest rate

4.41%

Amortization schedule

25 years

Balloon payment to be paid

$ 17,300,000

Avenel Business Park

Debt Instrument [Line Items]

Guarantor obligations, maximum exposure

6,300,000

Remaining loan balance

26,300,000

The Glen Mortgage | 4.41% mortgage maturing 2033

Debt Instrument [Line Items]

Remaining loan balance

$ 7,300,000

The Glen Mortgage | 4.69% fixed rate loan maturing in 2034

Debt Instrument [Line Items]

Loan amount

$ 22,900,000

Loan required periodic principal and interest payment

$ 129,800

Loan term

15 years

Loan fixed interest rate

4.69%

Amortization schedule

25 years

Balloon payment to be paid

$ 12,500,000

Countryside

Debt Instrument [Line Items]

Remaining loan balance

$ 12,700,000

Olde Forte Village | Four Point Six Five Maturing January Twenty Thirty Four [Member]

Debt Instrument [Line Items]

Loan amount

$ 22,100,000

Loan required periodic principal and interest payment

$ 124,700

Loan term

15 years

Loan fixed interest rate

4.65%

Amortization schedule

25 years

Balloon payment to be paid

$ 12,100,000

Briggs Chancy MarketPlace

Debt Instrument [Line Items]

Remaining loan balance

$ 12,400,000

Shops at Monocacy | 4.69% fixed rate loan maturing in 2034

Debt Instrument [Line Items]

Balloon payment to be paid

$ 15,100,000

Shops at Monocacy | Four Point Six Five Maturing January Twenty Thirty Four [Member]

Debt Instrument [Line Items]

Loan amount

28,500,000

Loan required periodic principal and interest payment

$ 152,600

Loan term

15 years

Loan fixed interest rate

4.14%

Amortization schedule

25 years

Thruway

Debt Instrument [Line Items]

Remaining loan balance

$ 35,600,000

Debt Covenant

Debt Instrument [Line Items]

Carrying value of properties collateralized

$ 1,100,000,000

$ 1,100,000,000

Credit agreement leverage ratio

60.00%

Interest coverage ratio required minimum

2

Required fixed charge coverage ratio

1.4

Scenario, Forecast | Park Van Ness Loan

Debt Instrument [Line Items]

Guarantor obligations, maximum exposure

$ 0

$ 3,300,000

Scenario, Forecast | Waycroft Construction Loan | 4.67% Construction To Permanent Loan Due 2035

Debt Instrument [Line Items]

Loan required periodic principal and interest payment

$ 887,900

Park Van Ness | Fixed rate mortgage notes payable | 4.88% due September 2032

Debt Instrument [Line Items]

Fixed rate mortgages

$ 71,600,000

Minimum | New Facility | Revolving Credit Facility | Line of Credit

Debt Instrument [Line Items]

Interest rate spread on LIBOR

1.35%

Minimum | New Facility | Revolving Credit Facility | Term Facility

Debt Instrument [Line Items]

Interest rate spread on LIBOR

1.30%

Maximum | New Facility | Revolving Credit Facility | Line of Credit

Debt Instrument [Line Items]

Interest rate spread on LIBOR

1.95%

Maximum | New Facility | Revolving Credit Facility | Term Facility

Debt Instrument [Line Items]

Interest rate spread on LIBOR

1.90%

Mortgage Notes Payable, Revol_4

Mortgage Notes Payable, Revolving Credit Facility, Interest Expense and Amortization of Deferred Debt Costs - Scheduled Maturities of All Debt, Including Scheduled Principal Amortization (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Balloon Payments
2020	$ 16,074
2021	11,012
2022	124,002
2023	84,225
2024	66,649
Thereafter	527,297
Balloon Payments	829,259
Scheduled Principal Amortization
2020	28,421
2021	29,025
2022	29,645
2023	30,065
2024	28,697
Thereafter	125,809
Scheduled Principal Amortization	271,662
Total
2020	44,495
2021	40,037
2022	153,647
2023	114,290
2024	95,346
Thereafter	653,106
Principal amount	1,100,921	$ 1,000,000
Unamortized deferred debt costs	9,733	$ 10,300
Net	$ 1,091,188

Mortgage Notes Payable, Revol_5

Mortgage Notes Payable, Revolving Credit Facility, Interest Expense and Amortization of Deferred Debt Costs - Interest Expense and Amortization of Deferred Debt Costs (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Debt Disclosure [Abstract]
Interest incurred	$ 52,044	$ 49,652	$ 49,322
Amortization of deferred debt costs	1,518	1,610	1,392
Capitalized interest	(11,480)	(6,222)	(3,489)
Interest expense	42,082	45,040	47,225
Less: Interest income	248	272	80
Interest expense, net and amortization of deferred debt costs	$ 41,834	$ 44,768	$ 47,145

Lease Agreements - Additional I

Lease Agreements - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Leases [Abstract]
Base rent	$ 185.7
Base rent (including straight-line rent)		$ 184.7	$ 181.1
Expense recoveries	36.5	35.5	35.3
Variable lease income	$ 0.9
Percentage rent		$ 1	$ 1.5

Lease Agreements - Future Contr

Lease Agreements - Future Contractual Payments Under Noncancelable Leases (Detail) $ in Thousands	Dec. 31, 2019USD ($)
Leases [Abstract]
2020	$ 166,227
2021	149,949
2022	126,101
2023	104,489
2024	75,172
Thereafter	260,141
Total future contractual payments	$ 882,079

Long-Term Lease Obligations - A

Long-Term Lease Obligations - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2019USD ($)property	Dec. 31, 2018USD ($)property	Dec. 31, 2017USD ($)
Leases Disclosure [Line Items]
Number of properties subject to noncancelable long-term lease | property	0	0
Rent expense	$ 806,500
Rent expense		$ 779,800	$ 774,700
90-year Ground Leasehold Interest
Leases Disclosure [Line Items]
Ground leasehold interest period	90 years
Minimum annual lease rent over lease term	$ 1
99-year Ground Lease
Leases Disclosure [Line Items]
Ground leasehold interest period	99 years
Minimum annual lease rent over lease term	$ 1
Percent of underlying land held under a 99-year ground lease	3.40%
Flagship Center
Leases Disclosure [Line Items]
Number of developed parcels | property	2

Equity and Noncontrolling Int_3

Equity and Noncontrolling Interest - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands, shares in Millions	Sep. 23, 2019	Sep. 17, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Oct. 17, 2019	Sep. 30, 2019
Class of Stock [Line Items]
Income attributable to noncontrolling interests			$ 12,473	$ 12,505	$ 12,411
Series C Cumulative Preferred Stock
Class of Stock [Line Items]
Depositary shares outstanding (in shares)				4.2
Liquidation preference (in usd per share)				$ 25
Annual dividend on depositary shares (in usd per share)				$ 1.71875
Preferred stock gross redemption price (in dollars per share)						$ 25
Preferred stock net redemption price (in dollars per share)						$ 25.07638
Percentage of redeemable preferred stock				6.875%
Depository shares to cumulative redeemable preferred stock ratio			1.00%
Dividend rate on preferred stock			6.875%
Series D Cumulative Redeemable Preferred Stock
Class of Stock [Line Items]
Depositary shares outstanding (in shares)			3
Liquidation preference (in usd per share)			$ 25
Annual dividend on depositary shares (in usd per share)			$ 1.53125
Percentage of redeemable preferred stock			6.125%
Depository shares to cumulative redeemable preferred stock ratio			1.00%
Dividend rate on preferred stock			6.125%
Series E Cumulative Redeemable Preferred Stock
Class of Stock [Line Items]
Depositary shares outstanding (in shares)	0.4	4
Liquidation preference (in usd per share)			$ 25				$ 25
Annual dividend on depositary shares (in usd per share)			$ 1.50
Percentage of redeemable preferred stock		6.00%	6.00%
Proceeds from shares sold	$ 9,500	$ 96,800

Equity and Noncontrolling Int_4

Equity and Noncontrolling Interest - Per Share Data (Details) - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Class of Stock [Line Items]
Weighted average common shares outstanding - basic (in shares)	23,009	22,383	21,901
Effect of dilutive options (in shares)	44	42	107
Weighted average common shares outstanding - diluted (in shares)	23,053	22,425	22,008
Average share price (in usd per share)	$ 53.41	$ 52.50	$ 61.63
Options
Class of Stock [Line Items]
Non-dilutive options (in shares)	633	492	0

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Detail)	Nov. 05, 2019USD ($)a$ / sharesshares	May 09, 2018shares	Dec. 08, 2016	May 31, 2018ashares	Aug. 31, 2016a	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Related Party Transaction [Line Items]
Company contribution to a multi employer 401K plan at discretionary amount of employee's cash compensation, maximum percentage						6.00%
Company contribution to a multi employer 401K plan at discretionary amount of employee's cash compensation, amount						$ 322,200	$ 345,900	$ 349,500
Deferred compensation, employee contribution, percentage						2.00%
Deferred compensation, employer contribution, percentage						3	3	3
Deferred compensation, company contribution, amount						$ 345,200	$ 282,500	$ 228,500
Deferred compensation, cumulative unfunded liability						3,100,000	2,700,000
Ancillary costs and expenses						8,400,000	8,400,000	8,100,000
Liability due to the Saul Organization for the company's share of these ancillary costs and expenses						918,700	933,400
Automatic renewal period			12 months
Insurance commissions and fees expense						$ 399,600	$ 407,900	$ 288,400
Contribution Agreement
Related Party Transaction [Line Items]
Number of partnership units issued in transaction (in shares) | shares	1,416,071
Value of units issued (in dollars per share) | $ / shares	$ 56
Value assigned to units issued	$ 79,300,000
BF Saul Real Estate Investment Trust | Ashbrook Marketplace
Related Party Transaction [Line Items]
Area of real estate property (in square feet) | a					13.7
Ashbrook Marketplace | BF Saul Real Estate Investment Trust
Related Party Transaction [Line Items]
Area of land | a				13.7
Limited partnership units issued (in shares) | shares		176,680		176,680
Land Contributed in Contribution Agreement | BF Saul Real Estate Investment Trust
Related Party Transaction [Line Items]
Area of land | a	6.8
Leasehold Interest Contributed in Contribution Agreement | BF Saul Real Estate Investment Trust
Related Party Transaction [Line Items]
Area of land | a	1.3

Stock Option Plan - Additional

Stock Option Plan - Additional Information (Detail)	Dec. 31, 2019USD ($)shares	May 03, 2019USD ($)person$ / sharesshares	May 11, 2018USD ($)person$ / sharesshares	May 05, 2017USD ($)person$ / sharesshares	Dec. 31, 2019USD ($)$ / sharesshares	Dec. 31, 2018$ / shares	Dec. 31, 2017$ / shares	Dec. 31, 2004shares
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Deferred compensation (in shares)	114,408				6,822
Exercise price of options (in usd per share) | $ / shares					$ 55.71	$ 49.46	$ 59.41
Allocated share based compensation | $					$ 1,600,000
Future expense | $	$ 2,600,000				$ 2,600,000
Stock options
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Expiration period								10 years
Stock options | Officer
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Option vesting period								4 years
Amended 2004 Plan | Stock options
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Authorized shares for a grant (in shares)								3,400,000
2017 Options
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price of options (in usd per share) | $ / shares				$ 59.41
Fair value stock option grant | $				$ 1,400,000
2017 Options | Officer
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Number of individuals granted options | person				20
Options vested				25.00%
Fair value stock option grant | $				$ 1,200,000
2017 Options | Director
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Number of individuals granted options | person				11
Fair value stock option grant | $				$ 165,600
2017 Options | Stock options
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Options granted to purchase stocks (in shares)				232,500
2017 Options | Stock options | Officer
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Option vesting period				4 years
2017 Options | Incentive stock option
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Options granted to purchase stocks (in shares)				21,492
2017 Options | Nonqualified stock options
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Options granted to purchase stocks (in shares)				211,008
2018 Options
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price of options (in usd per share) | $ / shares			$ 49.46
Fair value stock option grant | $			$ 1,400,000
2018 Options | Officer
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Number of individuals granted options | person			22
Options vested			25.00%
Fair value stock option grant | $			$ 1,200,000
2018 Options | Director
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Number of individuals granted options | person			11
Fair value stock option grant | $			$ 169,400
2018 Options | Stock options
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Options granted to purchase stocks (in shares)			245,000
2018 Options | Stock options | Officer
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Option vesting period			4 years
2018 Options | Incentive stock option
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Options granted to purchase stocks (in shares)			25,914
2018 Options | Nonqualified stock options
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Options granted to purchase stocks (in shares)			219,086
2019 Options
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price of options (in usd per share) | $ / shares		$ 55.71
Fair value stock option grant | $		$ 1,900,000
2019 Options | Officer
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Number of individuals granted options | person		23
Options vested		25.00%
Fair value stock option grant | $		$ 1,700,000
2019 Options | Director
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Number of individuals granted options | person		11
Fair value stock option grant | $		$ 226,600
2019 Options | Stock options
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Options granted to purchase stocks (in shares)		260,000
2019 Options | Stock options | Officer
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Option vesting period		4 years
2019 Options | Incentive stock option
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Options granted to purchase stocks (in shares)		34,651
2019 Options | Nonqualified stock options
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Options granted to purchase stocks (in shares)		225,349
Common Stock
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Shares due to exercise of employee stock options and issuance of directors' deferred stock (in shares)					7,058

Stock Option Plan - Stock Optio

Stock Option Plan - Stock Options Issued (Detail)	12 Months Ended
	Dec. 31, 2019$ / shares	Dec. 31, 2018$ / shares	Dec. 31, 2017$ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price (in usd per share)	$ 44.53	$ 42.98	$ 46.97
Directors | May 5, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price (in usd per share)	$ 59.41
Volatility	0.173
Expected life (years)	5 years
Assumed yield	3.45%
Risk-free rate	1.89%
Directors | May 11, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price (in usd per share)	$ 49.46
Volatility	0.192
Expected life (years)	5 years
Assumed yield	3.70%
Risk-free rate	2.84%
Directors | May 3, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price (in usd per share)	$ 55.71
Volatility	0.236
Expected life (years)	5 years
Assumed yield	3.75%
Risk-free rate	2.33%
Officers | May 5, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price (in usd per share)	$ 59.41
Volatility	0.170
Expected life (years)	7 years
Assumed yield	3.50%
Risk-free rate	2.17%
Officers | May 11, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price (in usd per share)	$ 49.46
Volatility	0.177
Expected life (years)	7 years
Assumed yield	3.75%
Risk-free rate	2.94%
Officers | May 3, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price (in usd per share)	$ 55.71
Volatility	0.206
Expected life (years)	7 years
Assumed yield	3.80%
Risk-free rate	2.43%

Stock Option Plan - Summary of

Stock Option Plan - Summary of Option Activity (Detail) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Shares
Outstanding at January 1 (in shares)	1,114,169	913,320	833,630
Granted (in shares)	260,000	245,000	232,500
Exercised (in shares)	(57,055)	(39,151)	(149,060)
Expired/Forfeited (in shares)	(7,500)	(5,000)	(3,750)
Outstanding December 31 (in shares)	1,309,614	1,114,169	913,320
Options exercisable (in shares)	763,614	600,919	430,945
Weighted Average Exercise Price
Outstanding at January 1 (in usd per share)	$ 52.40	$ 52.80	$ 49.92
Granted (in usd per share)	55.71	49.46	59.41
Exercised (in usd per share)	44.53	42.98	46.97
Expired/Forfeited (in usd per share)	56.07	54.78	53.73
Outstanding December 31 (in usd per share)	53.38	52.40	52.80
Exercisable at December 31 (in usd per share)	$ 52.43	$ 50.93	$ 48.94
Intrinsic value of options exercised	$ 0.6	$ 0.5	$ 2.2
Intrinsic value of options outstanding	2.5
Intrinsic value of options exercisable	$ 2
Closing price (in usd per share)	$ 52.78
Weighted average remaining life of options exercisable	5 years 10 months 24 days
Weighted average remaining life of options outstanding	7 years

Fair Value of Financial Instr_2

Fair Value of Financial Instruments - Additional Information (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Fair Value of Financial Instruments [Line Items]
Interest rate	3.55%	4.40%
Notes payable, fair value	$ 957,400	$ 927,000
Fixed rate mortgages	821,503	880,271
Fixed rate mortgage notes payable
Fair Value of Financial Instruments [Line Items]
Fixed rate mortgages	$ 938,400	$ 910,200

Distributions - Additional Info

Distributions - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	Jan. 31, 2020	Jan. 17, 2020	Jan. 15, 2020	Jan. 02, 2020	Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Dividends [Line Items]
Common stock issued, discount rate						3.00%
Common stock distributions (in usd per share)						$ 2.12	$ 2.08	$ 2.04
Dividends declared per common share outstanding (in usd per share)					$ 0.53
Distribution to limited partnership unitholders						$ 16,642	$ 15,981	$ 15,268
Dividend Income
Dividends [Line Items]
Common stock distributions (in usd per share)						$ 2	$ 1.61	$ 1.70
Return on Invested Capital
Dividends [Line Items]
Return of capital (in usd per share)					$ 0.12	0.12	0.47	0.34
Series C Preferred Stock
Dividends [Line Items]
Preferred stock dividend (in usd per share)						1.80	1.72	$ 1.72
6.125% Series D Preferred Stock, $0.01 Par Value
Dividends [Line Items]
Preferred stock dividend (in usd per share)						1.53	$ 1.05
6.000% Series E Preferred Stock, $0.01 Par Value
Dividends [Line Items]
Preferred stock dividend (in usd per share)						$ 0.06
Subsequent Event
Dividends [Line Items]
Common stock dividend paid		$ 12,300
Distribution to limited partnership unitholders	$ 4,200
Distributions partnership units (in usd per share)	$ 0.53
Preferred stock distributions			$ 2,800
Subsequent Event | 6.125% Series D Preferred Stock, $0.01 Par Value
Dividends [Line Items]
Dividends declared per preferred share outstanding (in usd per share)				$ 0.3828
Subsequent Event | 6.000% Series E Preferred Stock, $0.01 Par Value
Dividends [Line Items]
Dividends declared per preferred share outstanding (in usd per share)				$ 0.3750

Distributions - Summary of Dist

Distributions - Summary of Distributions Paid Including Activity in Plan as well as Limited Partnership Units Issued from Reinvestment of Unit Distributions (Detail) - USD ($) $ / shares in Units, $ in Thousands	Oct. 31, 2019	Jul. 31, 2019	Apr. 30, 2019	Jan. 31, 2019	Oct. 31, 2018	Jul. 31, 2018	Apr. 30, 2018	Jan. 31, 2018	Oct. 31, 2017	Jul. 31, 2017	Apr. 30, 2017	Jan. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Dividends [Line Items]
Preferred Stockholders													$ 12,390	$ 12,402	$ 12,375
Common Stockholders													48,568	46,306	44,576
Limited Partnership Unitholders													$ 16,642	$ 15,981	$ 15,268
Common Stock Shares Issued (in shares)													430,462,000	572,928	266,011
Limited Partnership Units Issued (in shares)													60,936,000	107,433	111,351
October 31
Dividends [Line Items]
Preferred Stockholders	$ 3,531				$ 2,953				$ 3,094
Common Stockholders	12,251				11,706				11,221
Limited Partnership Unitholders	$ 4,173				$ 4,062				$ 3,838
Common Stock Shares Issued (in shares)	104,558,000				216,476				82,991
Discounted Share Price (in usd per share)	$ 52.84				$ 49.34				$ 59.33
Limited Partnership Units Issued (in shares)	13,747,000				13,867				15,596
Average Unit Price (in usd per share)	$ 53.73				$ 50.20				$ 60.08
July 31
Dividends [Line Items]
Preferred Stockholders		$ 2,953				$ 2,953				$ 3,094
Common Stockholders		12,195				11,590				11,160
Limited Partnership Unitholders		$ 4,166				$ 4,055				$ 3,830
Common Stock Shares Issued (in shares)		105,753,000				201,500				85,731
Discounted Share Price (in usd per share)		$ 53.66				$ 51.68				$ 57.40
Limited Partnership Units Issued (in shares)		13,406,000				13,107				16,021
Average Unit Price (in usd per share)		$ 54.56				$ 52.60				$ 58.13
April 30
Dividends [Line Items]
Preferred Stockholders			$ 2,953				$ 2,672				$ 3,094
Common Stockholders			12,116				11,545				11,119
Limited Partnership Unitholders			$ 4,155				$ 3,942				$ 3,810
Common Stock Shares Issued (in shares)			99,804,000				85,202				51,003
Discounted Share Price (in usd per share)			$ 51.38				$ 47.54				$ 59.64
Limited Partnership Units Issued (in shares)			20,041,000				42,422				40,623
Average Unit Price (in usd per share)			$ 51.99				$ 47.83				$ 59.96
January 31
Dividends [Line Items]
Preferred Stockholders				$ 2,953				$ 3,824				$ 3,093
Common Stockholders				12,006				11,465				11,076
Limited Partnership Unitholders				$ 4,148				$ 3,922				$ 3,790
Common Stock Shares Issued (in shares)				120,347,000				69,750				46,286
Discounted Share Price (in usd per share)				$ 51.28				$ 52.71				$ 61.85
Limited Partnership Units Issued (in shares)				13,742,000				38,037				39,111
Average Unit Price (in usd per share)				$ 52.16				$ 53.03				$ 62.15

Interim Results (Unaudited) - S

Interim Results (Unaudited) - Summary of Results of Operations for Quarterly Periods (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Revenue	$ 56,582	$ 57,052	$ 58,141	$ 59,750	$ 58,119	$ 56,910	$ 56,081	$ 56,109	$ 231,525	$ 227,219	$ 226,299
Net Income	15,041	15,328	16,750	17,077	15,509	16,702	15,902	14,946
Net income attributable to Saul Centers, Inc.	12,818	12,226	13,232	13,447	12,269	13,155	12,543	12,587	51,723	50,554	48,257
Net income available to common stockholders	$ 6,464	$ 9,016	$ 10,279	$ 10,494	$ 9,316	$ 10,202	$ 9,590	$ 6,856	$ 36,253	$ 35,964	$ 35,882
Net income available to common stockholders per diluted share (in usd per share)	$ 0.27	$ 0.39	$ 0.45	$ 0.46	$ 0.41	$ 0.45	$ 0.43	$ 0.31	$ 1.57	$ 1.60	$ 1.63

Business Segments - Additional

Business Segments - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2019segment
Segment Reporting [Abstract]
Number of reportable business segments	2

Business Segments (Detail)

Business Segments (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Revenue	$ 56,582	$ 57,052	$ 58,141	$ 59,750	$ 58,119	$ 56,910	$ 56,081	$ 56,109	$ 231,525	$ 227,219	$ 226,299
Expenses									(57,933)	(55,578)	(54,686)
Income from real estate									173,592	171,641	171,613
Interest expense, net and amortization of deferred debt costs									(41,834)	(44,768)	(47,145)
General and administrative									(20,793)	(18,459)	(18,176)
Depreciation and amortization of deferred leasing costs									(46,333)	(45,861)	(45,694)
Change in fair value of derivatives									(436)	(3)	70
Gain on sale of property										509
Net income (loss)									64,196	63,059	60,668
Capital investment									135,663	128,650	119,994
Total assets	1,618,340				1,527,489				1,618,340	1,527,489	1,422,452
Operating Segments | Shopping Centers
Segment Reporting Information [Line Items]
Revenue									167,888	164,344	165,232
Expenses									(36,119)	(34,643)	(34,054)
Income from real estate									131,769	129,701	131,178
Interest expense, net and amortization of deferred debt costs									0	0	0
General and administrative									0	0	0
Depreciation and amortization of deferred leasing costs									(29,112)	(29,251)	(29,977)
Change in fair value of derivatives									0	0	0
Gain on sale of property										509
Net income (loss)									102,657	100,959	101,201
Capital investment									33,968	13,485	90,896
Total assets	980,096				971,321				980,096	971,321	974,061
Operating Segments | Mixed-Use Properties
Segment Reporting Information [Line Items]
Revenue									63,637	62,875	61,067
Expenses									(21,814)	(20,935)	(20,632)
Income from real estate									41,823	41,940	40,435
Interest expense, net and amortization of deferred debt costs									0	0	0
General and administrative									0	0	0
Depreciation and amortization of deferred leasing costs									(17,221)	(16,610)	(15,717)
Change in fair value of derivatives									0	0	0
Gain on sale of property										0
Net income (loss)									24,602	25,330	24,718
Capital investment									101,695	115,165	29,098
Total assets	625,183				537,500				625,183	537,500	438,283
Corporate
Segment Reporting Information [Line Items]
Revenue									0	0	0
Expenses									0	0	0
Income from real estate									0	0	0
Interest expense, net and amortization of deferred debt costs									(41,834)	(44,768)	(47,145)
General and administrative									(20,793)	(18,459)	(18,176)
Depreciation and amortization of deferred leasing costs									0	0	0
Change in fair value of derivatives									(436)	(3)	70
Gain on sale of property										0
Net income (loss)									(63,063)	(63,230)	(65,251)
Capital investment									0	0	0
Total assets	$ 13,061				$ 18,668				$ 13,061	$ 18,668	$ 10,108

Real Estate and Accumulated D_2

Real Estate and Accumulated Depreciation (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Real Estate Properties [Line Items]
Initial Basis	$ 984,390
Cost capitalized subsequent to acquisition	1,097,207
Land	453,322
Buildings	1,292,631
Construction in progress	335,644	$ 185,972
Total Purchase Price	2,081,597	1,948,165	$ 1,803,200	$ 1,700,813
Accumulated Depreciation	563,474	525,518	$ 488,166	$ 458,279
Book Value	1,518,123	1,422,647
Related Debt	821,503	880,271
Development land, related debt	108,623	$ 21,655
Total, related debt	938,421
Shopping Centers
Real Estate Properties [Line Items]
Initial Basis	841,335
Cost capitalized subsequent to acquisition	449,152
Land	415,424
Buildings	840,044
Construction in progress	35,019
Total Purchase Price	1,290,487
Accumulated Depreciation	381,382
Book Value	909,105
Related Debt	578,266
Shopping Centers | Ashbrook Marketplace, Ashburn, VA
Real Estate Properties [Line Items]
Initial Basis	8,938
Cost capitalized subsequent to acquisition	16,261
Land	3,066
Buildings	3,005
Construction in progress	19,128
Total Purchase Price	25,199
Accumulated Depreciation	8
Book Value	25,191
Related Debt	$ 0
Buildings and Improvements Depreciable Lives in Years	40 years
Shopping Centers | Ashburn Village, Ashburn, VA
Real Estate Properties [Line Items]
Initial Basis	$ 11,431
Cost capitalized subsequent to acquisition	20,514
Land	6,764
Buildings	25,077
Construction in progress	104
Total Purchase Price	31,945
Accumulated Depreciation	14,234
Book Value	17,711
Related Debt	$ 26,245
Buildings and Improvements Depreciable Lives in Years	40 years
Shopping Centers | Ashland Square Phase I, Dumfries, VA
Real Estate Properties [Line Items]
Initial Basis	$ 1,178
Cost capitalized subsequent to acquisition	7,508
Land	1,178
Buildings	5,298
Construction in progress	2,210
Total Purchase Price	8,686
Accumulated Depreciation	2,215
Book Value	6,471
Related Debt	$ 0
Shopping Centers | Ashland Square Phase I, Dumfries, VA | Minimum
Real Estate Properties [Line Items]
Buildings and Improvements Depreciable Lives in Years	20 years
Shopping Centers | Ashland Square Phase I, Dumfries, VA | Maximum
Real Estate Properties [Line Items]
Buildings and Improvements Depreciable Lives in Years	50 years
Shopping Centers | Beacon Center, Alexandria, VA
Real Estate Properties [Line Items]
Initial Basis	$ 24,161
Cost capitalized subsequent to acquisition	18,477
Land	22,674
Buildings	19,946
Construction in progress	18
Total Purchase Price	42,638
Accumulated Depreciation	15,335
Book Value	27,303
Related Debt	$ 36,206
Shopping Centers | Beacon Center, Alexandria, VA | Minimum
Real Estate Properties [Line Items]
Buildings and Improvements Depreciable Lives in Years	40 years
Shopping Centers | Beacon Center, Alexandria, VA | Maximum
Real Estate Properties [Line Items]
Buildings and Improvements Depreciable Lives in Years	50 years
Shopping Centers | BJ’s Wholesale Club, Alexandria, VA
Real Estate Properties [Line Items]
Initial Basis	$ 22,623
Cost capitalized subsequent to acquisition	0
Land	22,623
Buildings	0
Construction in progress	0
Total Purchase Price	22,623
Accumulated Depreciation	0
Book Value	22,623
Related Debt	$ 10,323
Buildings and Improvements Depreciable Lives in Years	0 years
Shopping Centers | Boca Valley Plaza, Boca Raton, FL
Real Estate Properties [Line Items]
Initial Basis	$ 16,720
Cost capitalized subsequent to acquisition	2,064
Land	5,735
Buildings	13,049
Construction in progress	0
Total Purchase Price	18,784
Accumulated Depreciation	5,252
Book Value	13,532
Related Debt	$ 9,234
Buildings and Improvements Depreciable Lives in Years	40 years
Shopping Centers | Boulevard, Fairfax, VA
Real Estate Properties [Line Items]
Initial Basis	$ 4,883
Cost capitalized subsequent to acquisition	4,709
Land	3,687
Buildings	5,905
Construction in progress	0
Total Purchase Price	9,592
Accumulated Depreciation	3,243
Book Value	6,349
Related Debt	$ 15,723
Buildings and Improvements Depreciable Lives in Years	40 years
Shopping Centers | Briggs Chaney MarketPlace, Silver Spring, MD
Real Estate Properties [Line Items]
Initial Basis	$ 27,037
Cost capitalized subsequent to acquisition	4,703
Land	9,789
Buildings	21,951
Construction in progress	0
Total Purchase Price	31,740
Accumulated Depreciation	9,333
Book Value	22,407
Related Debt	$ 0
Buildings and Improvements Depreciable Lives in Years	40 years
Shopping Centers | Broadlands Village, Ashburn, VA
Real Estate Properties [Line Items]
Initial Basis	$ 5,316
Cost capitalized subsequent to acquisition	34,586
Land	5,300
Buildings	34,589
Construction in progress	13
Total Purchase Price	39,902
Accumulated Depreciation	12,872
Book Value	27,030
Related Debt	$ 31,221
Shopping Centers | Broadlands Village, Ashburn, VA | Minimum
Real Estate Properties [Line Items]
Buildings and Improvements Depreciable Lives in Years	40 years
Shopping Centers | Broadlands Village, Ashburn, VA | Maximum
Real Estate Properties [Line Items]
Buildings and Improvements Depreciable Lives in Years	50 years
Shopping Centers | Burtonsville Town Square, Burtonsville, MD
Real Estate Properties [Line Items]
Initial Basis	$ 74,212
Cost capitalized subsequent to acquisition	5,612
Land	28,401
Buildings	50,915
Construction in progress	508
Total Purchase Price	79,824
Accumulated Depreciation	3,728
Book Value	76,096
Related Debt	$ 36,975
Shopping Centers | Burtonsville Town Square, Burtonsville, MD | Minimum
Real Estate Properties [Line Items]
Buildings and Improvements Depreciable Lives in Years	20 years
Shopping Centers | Burtonsville Town Square, Burtonsville, MD | Maximum
Real Estate Properties [Line Items]
Buildings and Improvements Depreciable Lives in Years	45 years
Shopping Centers | Countryside Marketplace, Sterling, VA
Real Estate Properties [Line Items]
Initial Basis	$ 28,912
Cost capitalized subsequent to acquisition	4,143
Land	7,666
Buildings	25,389
Construction in progress	0
Total Purchase Price	33,055
Accumulated Depreciation	10,518
Book Value	22,537
Related Debt	$ 0
Buildings and Improvements Depreciable Lives in Years	40 years
Shopping Centers | Cranberry Square, Westminster, MD
Real Estate Properties [Line Items]
Initial Basis	$ 31,578
Cost capitalized subsequent to acquisition	739
Land	6,700
Buildings	25,617
Construction in progress	0
Total Purchase Price	32,317
Accumulated Depreciation	5,497
Book Value	26,820
Related Debt	$ 15,917
Buildings and Improvements Depreciable Lives in Years	40 years
Shopping Centers | Cruse MarketPlace, Cumming, GA
Real Estate Properties [Line Items]
Initial Basis	$ 12,226
Cost capitalized subsequent to acquisition	689
Land	3,901
Buildings	9,014
Construction in progress	0
Total Purchase Price	12,915
Accumulated Depreciation	3,626
Book Value	9,289
Related Debt	$ 0
Buildings and Improvements Depreciable Lives in Years	40 years
Shopping Centers | Flagship Center, Rockville, MD
Real Estate Properties [Line Items]
Initial Basis	$ 160
Cost capitalized subsequent to acquisition	9
Land	169
Buildings	0
Construction in progress	0
Total Purchase Price	169
Accumulated Depreciation	0
Book Value	169
Related Debt	$ 0
Buildings and Improvements Depreciable Lives in Years	0 years
Shopping Centers | French Market, Oklahoma City, OK
Real Estate Properties [Line Items]
Initial Basis	$ 5,781
Cost capitalized subsequent to acquisition	14,269
Land	1,118
Buildings	18,929
Construction in progress	3
Total Purchase Price	20,050
Accumulated Depreciation	12,490
Book Value	7,560
Related Debt	$ 0
Buildings and Improvements Depreciable Lives in Years	50 years
Shopping Centers | Germantown, Germantown, MD
Real Estate Properties [Line Items]
Initial Basis	$ 2,034
Cost capitalized subsequent to acquisition	567
Land	2,034
Buildings	567
Construction in progress	0
Total Purchase Price	2,601
Accumulated Depreciation	409
Book Value	2,192
Related Debt	$ 0
Buildings and Improvements Depreciable Lives in Years	40 years
Shopping Centers | The Glen, Woodbridge, VA
Real Estate Properties [Line Items]
Initial Basis	$ 12,918
Cost capitalized subsequent to acquisition	8,351
Land	5,300
Buildings	15,942
Construction in progress	27
Total Purchase Price	21,269
Accumulated Depreciation	10,138
Book Value	11,131
Related Debt	$ 22,448
Buildings and Improvements Depreciable Lives in Years	40 years
Shopping Centers | Great Falls Center, Great Falls, VA
Real Estate Properties [Line Items]
Initial Basis	$ 41,750
Cost capitalized subsequent to acquisition	3,203
Land	14,766
Buildings	30,187
Construction in progress	0
Total Purchase Price	44,953
Accumulated Depreciation	9,497
Book Value	35,456
Related Debt	$ 10,774
Buildings and Improvements Depreciable Lives in Years	40 years
Shopping Centers | Hampshire Langley, Takoma, MD
Real Estate Properties [Line Items]
Initial Basis	$ 3,159
Cost capitalized subsequent to acquisition	3,549
Land	1,856
Buildings	4,635
Construction in progress	217
Total Purchase Price	6,708
Accumulated Depreciation	3,908
Book Value	2,800
Related Debt	$ 14,810
Buildings and Improvements Depreciable Lives in Years	40 years
Shopping Centers | Hunt Club Corners, Apopka, FL
Real Estate Properties [Line Items]
Initial Basis	$ 12,584
Cost capitalized subsequent to acquisition	4,409
Land	4,822
Buildings	12,171
Construction in progress	0
Total Purchase Price	16,993
Accumulated Depreciation	4,788
Book Value	12,205
Related Debt	$ 5,300
Buildings and Improvements Depreciable Lives in Years	40 years
Shopping Centers | Jamestown Place, Altamonte Springs, FL
Real Estate Properties [Line Items]
Initial Basis	$ 14,055
Cost capitalized subsequent to acquisition	1,950
Land	4,455
Buildings	11,550
Construction in progress	0
Total Purchase Price	16,005
Accumulated Depreciation	4,291
Book Value	11,714
Related Debt	$ 6,539
Buildings and Improvements Depreciable Lives in Years	40 years
Shopping Centers | Kentlands Square I, Gaithersburg, MD
Real Estate Properties [Line Items]
Initial Basis	$ 14,379
Cost capitalized subsequent to acquisition	840
Land	5,006
Buildings	9,711
Construction in progress	502
Total Purchase Price	15,219
Accumulated Depreciation	4,220
Book Value	10,999
Related Debt	$ 0
Buildings and Improvements Depreciable Lives in Years	40 years
Shopping Centers | Kentlands Square II, Gaithersburg, MD
Real Estate Properties [Line Items]
Initial Basis	$ 76,723
Cost capitalized subsequent to acquisition	2,733
Land	22,800
Buildings	56,270
Construction in progress	386
Total Purchase Price	79,456
Accumulated Depreciation	12,147
Book Value	67,309
Related Debt	$ 33,952
Buildings and Improvements Depreciable Lives in Years	40 years
Shopping Centers | Kentlands Place, Gaithersburg, MD
Real Estate Properties [Line Items]
Initial Basis	$ 1,425
Cost capitalized subsequent to acquisition	7,373
Land	1,425
Buildings	7,373
Construction in progress	0
Total Purchase Price	8,798
Accumulated Depreciation	4,241
Book Value	4,557
Related Debt	$ 0
Buildings and Improvements Depreciable Lives in Years	50 years
Shopping Centers | Lansdowne Town Center, Leesburg, VA
Real Estate Properties [Line Items]
Initial Basis	$ 6,545
Cost capitalized subsequent to acquisition	43,003
Land	6,546
Buildings	37,843
Construction in progress	5,159
Total Purchase Price	49,548
Accumulated Depreciation	16,291
Book Value	33,257
Related Debt	$ 30,719
Buildings and Improvements Depreciable Lives in Years	50 years
Shopping Centers | Leesburg Pike Plaza, Baileys Crossroads, VA
Real Estate Properties [Line Items]
Initial Basis	$ 2,418
Cost capitalized subsequent to acquisition	6,292
Land	1,132
Buildings	7,578
Construction in progress	0
Total Purchase Price	8,710
Accumulated Depreciation	6,159
Book Value	2,551
Related Debt	$ 14,414
Buildings and Improvements Depreciable Lives in Years	40 years
Shopping Centers | Lumberton Plaza, Lumberton, NJ
Real Estate Properties [Line Items]
Initial Basis	$ 4,400
Cost capitalized subsequent to acquisition	11,612
Land	950
Buildings	15,041
Construction in progress	21
Total Purchase Price	16,012
Accumulated Depreciation	13,379
Book Value	2,633
Related Debt	$ 0
Buildings and Improvements Depreciable Lives in Years	40 years
Shopping Centers | Metro Pike Center, Rockville, MD
Real Estate Properties [Line Items]
Initial Basis	$ 33,123
Cost capitalized subsequent to acquisition	4,605
Land	26,064
Buildings	7,729
Construction in progress	3,935
Total Purchase Price	37,728
Accumulated Depreciation	1,822
Book Value	35,906
Related Debt	$ 0
Buildings and Improvements Depreciable Lives in Years	40 years
Shopping Centers | Shops at Monocacy, Frederick, MD
Real Estate Properties [Line Items]
Initial Basis	$ 9,541
Cost capitalized subsequent to acquisition	13,994
Land	9,260
Buildings	14,275
Construction in progress	0
Total Purchase Price	23,535
Accumulated Depreciation	6,338
Book Value	17,197
Related Debt	$ 28,500
Buildings and Improvements Depreciable Lives in Years	50 years
Shopping Centers | Northrock, Warrenton, VA
Real Estate Properties [Line Items]
Initial Basis	$ 12,686
Cost capitalized subsequent to acquisition	15,429
Land	12,686
Buildings	15,423
Construction in progress	6
Total Purchase Price	28,115
Accumulated Depreciation	4,907
Book Value	23,208
Related Debt	$ 14,085
Buildings and Improvements Depreciable Lives in Years	50 years
Shopping Centers | Olde Forte Village, Ft. Washington, MD
Real Estate Properties [Line Items]
Initial Basis	$ 15,933
Cost capitalized subsequent to acquisition	6,721
Land	5,409
Buildings	17,245
Construction in progress	0
Total Purchase Price	22,654
Accumulated Depreciation	8,180
Book Value	14,474
Related Debt	$ 21,702
Buildings and Improvements Depreciable Lives in Years	40 years
Shopping Centers | Olney, Olney, MD
Real Estate Properties [Line Items]
Initial Basis	$ 4,963
Cost capitalized subsequent to acquisition	2,550
Land	3,079
Buildings	4,434
Construction in progress	0
Total Purchase Price	7,513
Accumulated Depreciation	3,358
Book Value	4,155
Related Debt	$ 11,952
Buildings and Improvements Depreciable Lives in Years	40 years
Shopping Centers | Orchard Park, Dunwoody, GA
Real Estate Properties [Line Items]
Initial Basis	$ 19,377
Cost capitalized subsequent to acquisition	1,461
Land	7,751
Buildings	13,087
Construction in progress	0
Total Purchase Price	20,838
Accumulated Depreciation	4,053
Book Value	16,785
Related Debt	$ 9,441
Buildings and Improvements Depreciable Lives in Years	40 years
Shopping Centers | Palm Springs Center, Altamonte Springs, FL
Real Estate Properties [Line Items]
Initial Basis	$ 18,365
Cost capitalized subsequent to acquisition	2,007
Land	5,739
Buildings	14,633
Construction in progress	0
Total Purchase Price	20,372
Accumulated Depreciation	5,593
Book Value	14,779
Related Debt	$ 7,262
Buildings and Improvements Depreciable Lives in Years	40 years
Shopping Centers | Ravenwood, Baltimore, MD
Real Estate Properties [Line Items]
Initial Basis	$ 1,245
Cost capitalized subsequent to acquisition	4,256
Land	703
Buildings	4,798
Construction in progress	0
Total Purchase Price	5,501
Accumulated Depreciation	3,308
Book Value	2,193
Related Debt	$ 13,606
Buildings and Improvements Depreciable Lives in Years	40 years
Shopping Centers | 11503 Rockville Pike/5541 Nicholson Lane, Rockville, MD
Real Estate Properties [Line Items]
Initial Basis	$ 26,561
Cost capitalized subsequent to acquisition	24
Land	22,113
Buildings	4,472
Construction in progress	0
Total Purchase Price	26,585
Accumulated Depreciation	1,032
Book Value	25,553
Related Debt	$ 0
Buildings and Improvements Depreciable Lives in Years	40 years
Shopping Centers | 1500/1580/1582/1584 Rockville Pike, Rockville, MD
Real Estate Properties [Line Items]
Initial Basis	$ 51,149
Cost capitalized subsequent to acquisition	2,714
Land	43,863
Buildings	7,490
Construction in progress	2,510
Total Purchase Price	53,863
Accumulated Depreciation	6,439
Book Value	47,424
Related Debt	0
Shopping Centers | Seabreeze Plaza, Palm Harbor, FL
Real Estate Properties [Line Items]
Initial Basis	24,526
Cost capitalized subsequent to acquisition	2,502
Land	8,665
Buildings	18,363
Construction in progress	0
Total Purchase Price	27,028
Accumulated Depreciation	6,746
Book Value	20,282
Related Debt	$ 15,019
Buildings and Improvements Depreciable Lives in Years	40 years
Shopping Centers | Market Place at Sea Colony, Bethany Beach, DE
Real Estate Properties [Line Items]
Initial Basis	$ 2,920
Cost capitalized subsequent to acquisition	246
Land	1,147
Buildings	2,019
Construction in progress	0
Total Purchase Price	3,166
Accumulated Depreciation	615
Book Value	2,551
Related Debt	$ 0
Buildings and Improvements Depreciable Lives in Years	40 years
Shopping Centers | Seven Corners, Falls Church, VA
Real Estate Properties [Line Items]
Initial Basis	$ 4,848
Cost capitalized subsequent to acquisition	44,612
Land	4,913
Buildings	44,522
Construction in progress	25
Total Purchase Price	49,460
Accumulated Depreciation	30,937
Book Value	18,523
Related Debt	$ 60,677
Buildings and Improvements Depreciable Lives in Years	40 years
Shopping Centers | Severna Park Marketplace, Severna Park, MD
Real Estate Properties [Line Items]
Initial Basis	$ 63,254
Cost capitalized subsequent to acquisition	526
Land	12,700
Buildings	51,080
Construction in progress	0
Total Purchase Price	63,780
Accumulated Depreciation	10,544
Book Value	53,236
Related Debt	$ 29,710
Buildings and Improvements Depreciable Lives in Years	40 years
Shopping Centers | Shops at Fairfax, Fairfax, VA
Real Estate Properties [Line Items]
Initial Basis	$ 2,708
Cost capitalized subsequent to acquisition	9,971
Land	992
Buildings	11,687
Construction in progress	0
Total Purchase Price	12,679
Accumulated Depreciation	8,676
Book Value	4,003
Related Debt	$ 10,482
Buildings and Improvements Depreciable Lives in Years	50 years
Shopping Centers | Smallwood Village Center, Waldorf, MD
Real Estate Properties [Line Items]
Initial Basis	$ 17,819
Cost capitalized subsequent to acquisition	8,332
Land	6,402
Buildings	19,743
Construction in progress	6
Total Purchase Price	26,151
Accumulated Depreciation	8,903
Book Value	17,248
Related Debt	$ 0
Buildings and Improvements Depreciable Lives in Years	40 years
Shopping Centers | Southdale, Glen Burnie, MD
Real Estate Properties [Line Items]
Initial Basis	$ 18,895
Cost capitalized subsequent to acquisition	25,100
Land	15,254
Buildings	28,740
Construction in progress	1
Total Purchase Price	43,995
Accumulated Depreciation	22,440
Book Value	21,555
Related Debt	$ 0
Buildings and Improvements Depreciable Lives in Years	40 years
Shopping Centers | Southside Plaza, Richmond, VA
Real Estate Properties [Line Items]
Initial Basis	$ 6,728
Cost capitalized subsequent to acquisition	11,338
Land	1,878
Buildings	16,188
Construction in progress	0
Total Purchase Price	18,066
Accumulated Depreciation	12,798
Book Value	5,268
Related Debt	$ 0
Buildings and Improvements Depreciable Lives in Years	40 years
Shopping Centers | South Dekalb Plaza, Atlanta, GA
Real Estate Properties [Line Items]
Initial Basis	$ 2,474
Cost capitalized subsequent to acquisition	4,449
Land	703
Buildings	6,220
Construction in progress	0
Total Purchase Price	6,923
Accumulated Depreciation	5,088
Book Value	1,835
Related Debt	$ 0
Buildings and Improvements Depreciable Lives in Years	40 years
Shopping Centers | Thruway, Winston-Salem, NC
Real Estate Properties [Line Items]
Initial Basis	$ 7,848
Cost capitalized subsequent to acquisition	26,336
Land	7,693
Buildings	26,447
Construction in progress	44
Total Purchase Price	34,184
Accumulated Depreciation	18,682
Book Value	15,502
Related Debt	$ 0
Buildings and Improvements Depreciable Lives in Years	40 years
Shopping Centers | Village Center, Centreville, VA
Real Estate Properties [Line Items]
Initial Basis	$ 16,502
Cost capitalized subsequent to acquisition	2,636
Land	7,851
Buildings	11,287
Construction in progress	0
Total Purchase Price	19,138
Accumulated Depreciation	7,380
Book Value	11,758
Related Debt	$ 12,555
Buildings and Improvements Depreciable Lives in Years	40 years
Shopping Centers | Westview Village, Frederick, MD
Real Estate Properties [Line Items]
Initial Basis	$ 6,047
Cost capitalized subsequent to acquisition	25,225
Land	6,047
Buildings	25,216
Construction in progress	9
Total Purchase Price	31,272
Accumulated Depreciation	9,483
Book Value	21,789
Related Debt	$ 0
Buildings and Improvements Depreciable Lives in Years	50 years
Shopping Centers | White Oak, Silver Spring, MD
Real Estate Properties [Line Items]
Initial Basis	$ 6,277
Cost capitalized subsequent to acquisition	5,771
Land	4,649
Buildings	7,212
Construction in progress	187
Total Purchase Price	12,048
Accumulated Depreciation	6,169
Book Value	5,879
Related Debt	$ 22,475
Buildings and Improvements Depreciable Lives in Years	40 years
Shopping Centers | Other Buildings / Improvements
Real Estate Properties [Line Items]
Cost capitalized subsequent to acquisition	$ 182
Buildings	182
Construction in progress	0
Total Purchase Price	182
Accumulated Depreciation	72
Book Value	110
Related Debt	0
Mixed-Use Properties
Real Estate Properties [Line Items]
Initial Basis	43,967
Cost capitalized subsequent to acquisition	437,116
Land	28,496
Buildings	452,587
Construction in progress	0
Total Purchase Price	481,083
Accumulated Depreciation	182,092
Book Value	298,991
Related Debt	$ 249,956
Mixed-Use Properties | 1500/1580/1582/1584 Rockville Pike, Rockville, MD | Acquisition Date One
Real Estate Properties [Line Items]
Buildings and Improvements Depreciable Lives in Years	5 years
Mixed-Use Properties | 1500/1580/1582/1584 Rockville Pike, Rockville, MD | Acquisition Date Two
Real Estate Properties [Line Items]
Buildings and Improvements Depreciable Lives in Years	10 years
Mixed-Use Properties | 1500/1580/1582/1584 Rockville Pike, Rockville, MD | Acquisition Date Three
Real Estate Properties [Line Items]
Buildings and Improvements Depreciable Lives in Years	5 years
Mixed-Use Properties | 1500/1580/1582/1584 Rockville Pike, Rockville, MD | Acquisition Date Four
Real Estate Properties [Line Items]
Buildings and Improvements Depreciable Lives in Years	4 years
Mixed-Use Properties | Avenel Business Park, Gaithersburg, MD
Real Estate Properties [Line Items]
Initial Basis	$ 21,459
Cost capitalized subsequent to acquisition	32,976
Land	3,756
Buildings	50,679
Construction in progress	0
Total Purchase Price	54,435
Accumulated Depreciation	39,261
Book Value	15,174
Related Debt	$ 26,260
Mixed-Use Properties | Avenel Business Park, Gaithersburg, MD | Minimum
Real Estate Properties [Line Items]
Buildings and Improvements Depreciable Lives in Years	35 years
Mixed-Use Properties | Avenel Business Park, Gaithersburg, MD | Maximum
Real Estate Properties [Line Items]
Buildings and Improvements Depreciable Lives in Years	40 years
Mixed-Use Properties | Clarendon Center, Arlington, VA (1)
Real Estate Properties [Line Items]
Initial Basis	$ 12,753
Cost capitalized subsequent to acquisition	186,210
Land	16,287
Buildings	182,676
Construction in progress	0
Total Purchase Price	198,963
Accumulated Depreciation	46,856
Book Value	152,107
Related Debt	$ 98,611
Buildings and Improvements Depreciable Lives in Years	50 years
Mixed-Use Properties | Park Van Ness, Washington, DC
Real Estate Properties [Line Items]
Initial Basis	$ 2,242
Cost capitalized subsequent to acquisition	91,699
Land	2,242
Buildings	91,699
Construction in progress	0
Total Purchase Price	93,941
Accumulated Depreciation	10,757
Book Value	83,184
Development land, related debt	$ 68,095
Buildings and Improvements Depreciable Lives in Years	50 years
Mixed-Use Properties | 601 Pennsylvania Ave., Washington, DC
Real Estate Properties [Line Items]
Initial Basis	$ 5,479
Cost capitalized subsequent to acquisition	69,129
Land	5,667
Buildings	68,941
Construction in progress	0
Total Purchase Price	74,608
Accumulated Depreciation	57,038
Book Value	17,570
Related Debt	$ 0
Buildings and Improvements Depreciable Lives in Years	35 years
Mixed-Use Properties | Washington Square, Alexandria, VA
Real Estate Properties [Line Items]
Initial Basis	$ 2,034
Cost capitalized subsequent to acquisition	57,102
Land	544
Buildings	58,592
Construction in progress	0
Total Purchase Price	59,136
Accumulated Depreciation	28,180
Book Value	30,956
Related Debt	$ 56,990
Buildings and Improvements Depreciable Lives in Years	50 years
Development Land
Real Estate Properties [Line Items]
Initial Basis	$ 99,088
Cost capitalized subsequent to acquisition	210,939
Land	9,402
Buildings	0
Construction in progress	300,625
Total Purchase Price	310,027
Accumulated Depreciation	0
Book Value	310,027
Development land, related debt	110,199
Development Land | Ashland Square Phase II, Manassas, VA
Real Estate Properties [Line Items]
Initial Basis	5,292
Cost capitalized subsequent to acquisition	2,280
Land	7,028
Buildings	0
Construction in progress	544
Total Purchase Price	7,572
Accumulated Depreciation	0
Book Value	7,572
Development land, related debt	0
Development Land | New Market, New Market, MD
Real Estate Properties [Line Items]
Initial Basis	2,088
Cost capitalized subsequent to acquisition	286
Land	2,374
Buildings	0
Construction in progress	0
Total Purchase Price	2,374
Accumulated Depreciation	0
Book Value	2,374
Development land, related debt	0
Development Land | The Waycroft, Arlington, VA
Real Estate Properties [Line Items]
Initial Basis	52,067
Cost capitalized subsequent to acquisition	203,376
Land	0
Buildings	0
Construction in progress	255,443
Total Purchase Price	255,443
Accumulated Depreciation	0
Book Value	255,443
Development land, related debt	110,199
Development Land | 7316 Wisconsin Avenue, Bethesda, MD
Real Estate Properties [Line Items]
Initial Basis	39,641
Cost capitalized subsequent to acquisition	4,997
Land	0
Buildings	0
Construction in progress	44,638
Total Purchase Price	44,638
Accumulated Depreciation	0
Book Value	44,638
Development land, related debt	$ 0
Buildings and Improvements Depreciable Lives in Years

Real Estate and Accumulated D_3

Real Estate and Accumulated Depreciation - Estimated Useful Lives of Assets (Detail)	12 Months Ended
	Dec. 31, 2019
Base building | Minimum
Property Plant and Equipment Estimated Useful Lives [Line Items]
Estimated useful life	35 years
Base building | Maximum
Property Plant and Equipment Estimated Useful Lives [Line Items]
Estimated useful life	50 years
Building components | Maximum
Property Plant and Equipment Estimated Useful Lives [Line Items]
Estimated useful life	20 years

Real Estate and Accumulated D_4

Real Estate and Accumulated Depreciation - Additional Information (Detail) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation Disclosure [Abstract]
Real estate investments for federal income tax	$ 1,330	$ 1,350

Real Estate and Accumulated D_5

Real Estate and Accumulated Depreciation - Changes in Total Real Estate Investments and Related Accumulated Depreciation (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Total real estate investments:
Balance, beginning of year	$ 1,948,165	$ 1,803,200	$ 1,700,813
Acquisitions	0	48,579	77,258
Improvements	135,966	98,917	42,640
Retirements	(2,534)	(2,531)	(17,511)
Balance, end of year	2,081,597	1,948,165	1,803,200
Total accumulated depreciation:
Balance, beginning of year	525,518	488,166	458,279
Depreciation expense	40,490	39,768	40,197
Retirements	(2,534)	(2,416)	(10,310)
Balance, end of year	$ 563,474	$ 525,518	$ 488,166