Saul Centers (BFS) 10-K 26 Feb 19 2018 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2018	Feb. 20, 2019	Jun. 30, 2018
Document And Entity Information [Abstract]
Document type	10-K
Amendment flag	false
Document period end date	Dec. 31, 2018
Document fiscal year focus	2,018
Document fiscal period focus	FY
Trading symbol	BFS
Entity registrant name	SAUL CENTERS INC
Entity central index key	907,254
Current fiscal year end date	--12-31
Entity well-known seasoned issuer	Yes
Entity current reporting status	Yes
Entity voluntary filers	No
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity filer category	Large Accelerated Filer
Entity common stock, shares outstanding		22.7
Entity public float			$ 673.7

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Real estate investments
Land	$ 488,918	$ 450,256
Buildings and equipment	1,273,275	1,261,830
Construction in progress	185,972	91,114
Total Purchase Price	1,948,165	1,803,200
Accumulated depreciation	(525,518)	(488,166)
Book Value	1,422,647	1,315,034
Cash and cash equivalents	14,578	10,908
Accounts receivable and accrued income, net	53,876	54,057
Deferred leasing costs, net	28,083	27,255
Prepaid expenses, net	5,175	5,248
Other assets	3,130	9,950
Total assets	1,527,489	1,422,452
Liabilities
Mortgage notes payable	880,271	897,888
Term loan facility payable	74,591	0
Revolving credit facility payable	45,329	60,734
Construction loan payable	21,655	0
Dividends and distributions payable	19,153	18,520
Accounts payable, accrued expenses and other liabilities	32,419	23,123
Deferred income	28,851	29,084
Total liabilities	1,102,269	1,029,349
Equity
Common stock, $0.01 par value, 40,000,000 shares authorized, 22,739,207 and 22,123,128 shares issued and outstanding, respectively	227	221
Additional paid-in capital	384,533	352,590
Distributions in excess of accumulated earnings	(208,593)	(197,710)
Accumulated other comprehensive loss	(255)	(696)
Total Saul Centers, Inc. equity	355,912	334,405
Noncontrolling interests	69,308	58,698
Total equity	425,220	393,103
Total liabilities and equity	1,527,489	1,422,452
Series C Cumulative Preferred Stock
Equity
Preferred stock, 1,000,000 shares authorized, Series C Cumulative Redeemable, 42,000 and 72,000 shares issued and outstanding, Series D Cumulative Redeemable, 30,000 and 0 shares issued and outstanding	105,000	180,000
Series D Cumulative Redeemable Preferred Stock
Equity
Preferred stock, 1,000,000 shares authorized, Series C Cumulative Redeemable, 42,000 and 72,000 shares issued and outstanding, Series D Cumulative Redeemable, 30,000 and 0 shares issued and outstanding	$ 75,000	$ 0

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2018	Dec. 31, 2017
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)	22,739,207	22,123,128
Common stock, shares outstanding (in shares)	22,739,207	22,123,128
Series C Cumulative Preferred Stock
Cumulative redeemable preferred stock, shares issued (in shares)	42,000	72,000
Cumulative redeemable preferred stock, shares outstanding (in shares)	42,000	72,000
Series D Cumulative Redeemable Preferred Stock
Cumulative redeemable preferred stock, shares issued (in shares)	30,000	0
Cumulative redeemable preferred stock, shares outstanding (in shares)	30,000	0

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property revenue
Base rent	$ 184,684	$ 181,141	$ 172,381
Expense recoveries	35,500	35,300	34,300
Percentage rent	994	1,458	1,379
Total property revenue	227,904	227,205	217,019
Property expenses
Operating income	62,553	60,598	55,713
Other revenue	272	80	51
Interest expense and amortization of deferred debt costs	45,040	47,225	45,683
Depreciation and amortization of deferred leasing costs	45,861	45,694	44,417
General and administrative	18,459	18,176	17,496
Acquisition related costs	0	0	60
Change in fair value of derivatives	(3)	70	(6)
Gains on sale of property	509	0	1,013
Net income (loss)	63,059	60,668	56,720
Income attributable to noncontrolling interests	(12,505)	(12,411)	(11,441)
Net income attributable to Saul Centers, Inc.	50,554	48,257	45,279
Extinguishment of issuance costs upon redemption of preferred shares	(2,328)	0	0
Preferred stock dividends	(12,262)	(12,375)	(12,375)
Net income available to common stockholders	$ 35,964	$ 35,882	$ 32,904
Per share net income available to common stockholders
Basic (in usd per share)	$ 1.61	$ 1.64	$ 1.53
Diluted (in usd per share)	$ 1.60	$ 1.63	$ 1.52
Expense recoveries
Property revenue
Expense recoveries	$ 35,537	$ 35,347	$ 34,269
Other
Property revenue
Other	6,689	9,259	8,990
Property expenses
Property expenses
Property operating expenses	28,202	27,689	27,527
Provision for credit losses	685	906	1,494
Real estate taxes	27,376	26,997	24,680
Total property expenses	56,263	55,592	53,701
Operating income	171,641	171,613	163,318
Total other expenses
Property expenses
Total property expenses	$ 109,360	$ 111,095	$ 107,656

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 63,059	$ 60,668	$ 56,720
Other comprehensive income
Unrealized gain on cash flow hedge	594	812	678
Total comprehensive income	63,653	61,480	57,398
Comprehensive income attributable to noncontrolling interests	(12,658)	(12,620)	(11,616)
Total comprehensive income attributable to Saul Centers, Inc.	50,995	48,860	45,782
Extinguishment of issuance costs upon redemption of preferred shares	(2,328)	0	0
Preferred dividends	(12,262)	(12,375)	(12,375)
Total comprehensive income available to common stockholders	$ 36,405	$ 36,485	$ 33,407

Consolidated Statements of Equi

Consolidated Statements of Equity - USD ($) $ in Thousands	Total	Dividend paid	Dividend declared	Series D Cumulative Redeemable Preferred Stock	Series D Cumulative Redeemable Preferred StockDividend paid	Series D Cumulative Redeemable Preferred StockDividend declared	Series C Cumulative Preferred Stock	Series C Cumulative Preferred StockDividend paid	Series C Cumulative Preferred StockDividend declared	Preferred Stock	Preferred StockSeries D Cumulative Redeemable Preferred Stock	Preferred StockSeries C Cumulative Preferred Stock	Common Stock	Additional Paid-in Capital	Additional Paid-in CapitalSeries D Cumulative Redeemable Preferred Stock	Additional Paid-in CapitalSeries C Cumulative 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 D Cumulative Redeemable Preferred StockDividend paid	Distributions in Excess of Accumulated EarningsSeries D Cumulative Redeemable Preferred StockDividend 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	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 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 C Cumulative Preferred Stock	Total Saul Centers, Inc.Series C Cumulative Preferred StockDividend paid	Total Saul Centers, Inc.Series C Cumulative Preferred StockDividend declared	Noncontrolling Interests	Noncontrolling InterestsDividend paid	Noncontrolling InterestsDividend declared
Beginning balance at Dec. 31, 2015	$ 353,727									$ 180,000			$ 213	$ 305,008			$ (180,091)								$ (1,802)	$ 303,328									$ 50,399
Issuance of common stock:
Shares issued pursuant to dividend reinvestment plan	10,311												2	10,309												10,311
Shares issued due to exercise of employee stock options and issuance of directors' deferred stock	12,856												2	12,854												12,856
Issuance of partnership units pursuant to dividend reinvestment plan	6,910																																		6,910
Net income	56,720																45,279									45,279									11,441
Change in unrealized loss on cash flow hedge	678																								503	503									175
Preferred stock distributions:
Preferred stock distributions								$ (9,282)	$ (3,093)														$ (9,282)	$ (3,093)									$ (9,282)	$ (3,093)
Common stock distributions		$ (40,720)																$ (30,328)									$ (30,328)									$ (10,392)
Distributions payable common stock and distributions payable partnership units			$ (14,858)																$ (11,069)									$ (11,069)									$ (3,789)
Ending 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 pursuant to dividend reinvestment plan	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 Series D 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 pursuant to dividend reinvestment plan	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					$ (3,164)	$ (1,148)		$ (6,145)	$ (1,805)											$ (3,164)	$ (1,148)		$ (6,145)	$ (1,805)						$ (3,164)	$ (1,148)		$ (6,145)	$ (1,805)
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

Consolidated Statements of Eq_2

Consolidated Statements of Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Shares issued pursuant to dividend reinvestment plan (in shares)	572,928	266,011	186,797
Shares due to exercise of employee stock options and issuance of directors' deferred stock (in shares)	43,150	152,758	251,323
Issuance of partnership units pursuant to dividend reinvestment plan (in shares)	107,433	111,351	124,758
Issuance of partnership units (in shares)	284,113
Series D Cumulative Redeemable Preferred Stock
Issuance of Series D Cumulative preferred stock (in shares)	30,000
Series C Cumulative Preferred Stock
Redemption of Series C Cumulative preferred stock (in shares)	30,000
Dividend declared
Distributions payable common stock and partnership units (in usd per share)	$ 0.53	$ 0.52	$ 0.51
Dividend declared | Series D Cumulative Redeemable Preferred Stock
Distributions payable on preferred stock (in usd per share)	38.28
Dividend declared | Series C Cumulative Preferred Stock
Distributions payable on preferred stock (in usd per share)	$ 42.97	$ 42.97	$ 42.97

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities:
Net income		$ 63,059	$ 60,668	$ 56,720
Adjustments to reconcile net income to net cash provided by operating activities:
Change in fair value of derivatives		3	(70)	6
Gains on sales of properties		(509)	0	(1,013)
Depreciation and amortization of deferred leasing costs		45,861	45,694	44,417
Amortization of deferred debt costs		1,610	1,392	1,343
Non cash compensation costs of stock grants and options		1,766	1,672	1,603
Provision for credit losses		685	906	1,494
Increase in accounts receivable and accrued income		(336)	(1,643)	(3,525)
Additions to deferred leasing costs		(6,034)	(4,615)	(4,633)
Increase (decrease) in prepaid expenses		73	(294)	(399)
(Increase) decrease in other assets		3,681	1,374	(6,368)
Increase in accounts payable, accrued expenses and other liabilities		225	1,125	921
Increase (decrease) in deferred income		255	(2,759)	(1,476)
Net cash provided by operating activities		110,339	103,450	89,090
Cash flows from investing activities:
Acquisitions of real estate investments	[1]	(40,836)	(79,499)	(48,250)
Additions to real estate investments		(12,883)	(17,653)	(15,564)
Additions to development and redevelopment projects		(76,257)	(22,842)	(27,231)
Proceeds from sale of properties	[2]	1,326	6,688	4,771
Net cash used in investing activities		(128,650)	(113,306)	(86,274)
Cash flows from financing activities:
Proceeds from mortgage notes payable		54,900	100,000	11,250
Repayments on mortgage notes payable		(72,572)	(55,679)	(24,653)
Proceeds from term loan facility		75,000	0	0
Proceeds from revolving credit facility		102,000	63,000	78,500
Repayments on revolving credit facility		(116,000)	(51,000)	(57,500)
Proceeds from construction loans payable		23,332	1,437	24,937
Additions to deferred debt costs		(3,233)	(2,583)	(125)
Proceeds from the issuance of:
Common stock		30,503	22,751	21,564
Partnership units	[1]	5,383	6,735	6,910
Preferred stock redemption costs		(12)	0	0
Distributions to:
Distributions to preferred stockholders		(12,402)	(12,375)	(12,375)
Common stockholders		(46,306)	(44,576)	(39,472)
Noncontrolling interests		(15,981)	(15,268)	(13,533)
Net cash provided by (used in) financing activities		21,981	12,442	(4,497)
Net increase (decrease) in cash and cash equivalents		3,670	2,586	(1,681)
Cash and cash equivalents, beginning of year		10,908	8,322	10,003
Cash and cash equivalents, end of year		14,578	10,908	8,322
Supplemental disclosure of cash flow information:
Cash paid for interest		43,561	45,713	44,066
Increase (decrease) in accrued real estate investments and development costs		9,663	2,097	(7,098)
Series D Cumulative Redeemable Preferred Stock
Proceeds from the issuance of:
Series D preferred stock		72,369	0	0
Distributions to:
Distributions to preferred stockholders		(3,164)	0	0
Series C Cumulative Preferred Stock
Proceeds from the issuance of:
Series C preferred stock redemption		(75,000)	0	0
Distributions to:
Distributions to preferred stockholders		$ (9,238)	(12,375)	$ (12,375)
Great Eastern Shopping Center
Supplemental disclosure of cash flow information:
Seller financing			$ 1,275
[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 sales 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.

Organization, Formation, and Ba

Organization, Formation, and Basis of Presentation	12 Months Ended
	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization, Formation, and Basis of Presentation	ORGANIZATION, FORMATION, AND BASIS OF PRESENTATION Organization 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 and Chief Executive Officer of Saul Centers. Formation and Structure of Company 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 center 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 following table lists the significant properties acquired, developed and/or disposed of by the Company since January 1, 2016 . Name of Property Location Type Year of Acquisition/ Development/ Disposal Acquisitions Burtonsville Town Square Burtonsville, Maryland Shopping Center 2017 7316 Wisconsin Avenue Bethesda, Maryland Mixed-Use 2018 Developments 750 N. Glebe Road Arlington, Virginia Mixed-Use 2017-2018 Ashbrook Marketplace Ashburn, Virginia Shopping Center 2018 Dispositions Crosstown Business Center Tulsa, Oklahoma Mixed-Use 2016 Great Eastern District Heights, Maryland Shopping Center 2017 As of December 31, 2018 , the Company’s properties (the “Current Portfolio Properties”) consisted of 49 shopping center properties (the “Shopping Centers”), seven mixed-use properties, which are comprised of office, retail and multi-family residential uses (the “Mixed-Use Properties”) and four (non-operating) development properties. Basis of Presentation The accompanying financial statements are presented on the historical cost basis of the Saul Organization because of affiliated ownership and common management and because the assets and liabilities were the subject of a business combination with the Operating Partnership, the Subsidiary Partnerships and Saul Centers, all newly formed entities with no prior operations.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Nature of Operations 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, 2018 , 32 of the Shopping Centers were anchored by a grocery store and offer primarily day-to-day necessities and services. Two retail tenants, Giant Food ( 4.7% ), a tenant at ten Shopping Centers and Capital One Bank ( 2.7% ), a tenant at 17 properties, individually accounted for 2.5% or more of the Company’s total revenue for the year ended December 31, 2018 . Principles of Consolidation The accompanying consolidated financial statements include the accounts of Saul Centers, its subsidiaries, and the Operating Partnership and Subsidiary Partnerships which are majority owned by Saul Centers. 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 74.3% 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. Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States 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. Actual results could differ from those estimates. Real Estate Investment Properties The Company purchases real estate investment properties from time to time and records assets acquired and liabilities assumed, including land, buildings, and intangibles related to in-place leases and customer relationships, based on their relative fair values. The fair value of buildings generally is determined as if the buildings were vacant upon acquisition and then subsequently leased at market rental rates and considers the present value of all cash flows expected to be generated by the property including an initial lease up period. From time to time the Company may purchase a property for future development purposes. The property may be improved with an existing structure that would be demolished as part of the development. In such cases, the fair value of the building may be determined based only on existing leases and not include estimated cash flows related to future leases. In certain circumstances, such as if the building is vacant and the Company intends to demolish the building in the near term, the entire purchase price will be allocated to land. The Company determines the fair value of above and below market intangibles associated with in-place leases by assessing the net effective rent and remaining term of the lease relative to market terms for similar leases at acquisition taking into consideration the remaining contractual lease period, renewal periods, and the likelihood of the tenant exercising its renewal options. The fair value of a below market lease component is recorded as deferred income and accreted as additional lease revenue over the remaining contractual lease period. If the fair value of the below market lease intangible includes fair value associated with a renewal option, such amounts are not accreted until the renewal option is exercised. If the renewal option is not exercised the value is recognized at that time. The fair value of above market lease intangibles is recorded as a deferred asset and is amortized as a reduction of lease revenue over the remaining contractual lease term. The Company determines the fair value of at-market in-place leases considering the cost of acquiring similar leases, the foregone rents associated with the lease-up period and carrying costs associated with the lease-up period. Intangible assets associated with at-market in-place leases are amortized as additional expense over the remaining contractual lease term. To the extent customer relationship intangibles are present in an acquisition, the fair values of the intangibles are amortized over the lives of the customer relationships. The Company has never recorded a customer relationship intangible asset. Acquisition-related transaction costs are either (a) expensed as incurred when related to business combinations or (b) capitalized to land and/or building when related to asset acquisitions. 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 2018 , 2017 , or 2016 . Interest, real estate taxes, development related salary costs and other carrying costs are capitalized on projects under development and construction. Once construction is substantially completed and the assets are placed in service, their rental income, real estate tax expense, property operating expenses (consisting of payroll, repairs and maintenance, utilities, insurance and other property related expenses) and depreciation are included in current operations. Property operating expenses are charged to operations as incurred. Interest expense capitalized totaled $6.2 million , $3.5 million , and $ 2.5 million during 2018 , 2017 , and 2016 , respectively. Commercial development projects are considered substantially complete and available for occupancy upon completion of tenant improvements, but no later than one year from the cessation of major construction activity. Multi-family residential development projects are considered substantially complete and available for occupancy upon receipt of the certificate of occupancy from the appropriate licensing authority. Substantially completed portions of a project are accounted for as separate projects. 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, 2018 , 2017 , and 2016 , was $39.8 million , $40.2 million , and $38.8 million , respectively. Repairs and maintenance expense totaled $11.9 million , $11.6 million , and $11.8 million for 2018 , 2017 , and 2016 , respectively, and is included in property operating expenses in the accompanying consolidated financial statements. 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 $28.1 million and $27.3 million , net of accumulated amortization of approximately $37.7 million and $35.3 million , as of December 31, 2018 and 2017 , respectively. Amortization expense, which is included in Depreciation and amortization of deferred leasing costs in the Consolidated Statements of Operations, totaled approximately $6.1 million , $5.5 million , and $5.6 million , for the years ended December 31, 2018 , 2017 , and 2016 , respectively. Construction in Progress Construction in progress includes 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) 2018 2017 N. Glebe Road $ 162,176 $ 83,462 Ashbrook Marketplace 11,124 — Other 12,672 7,652 Total $ 185,972 $ 91,114 Accounts Receivable and Accrued Income Accounts receivable primarily represent amounts currently due from tenants in accordance with the terms of the respective leases. 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 $0.6 million and $0.4 million , at December 31, 2018 and 2017 , respectively. (In thousands) Year ended December 31, 2018 2017 2016 Beginning Balance $ 405 $ 1,958 $ 1,263 Provision for Credit Losses 685 906 1,494 Charge-offs (531 ) (2,459 ) (799 ) Ending Balance $ 559 $ 405 $ 1,958 In addition to rents due currently, accounts receivable also includes $43.3 million and $44.1 million , at December 31, 2018 and 2017 , respectively, net of allowance for doubtful accounts totaling $0.1 million and $0.2 million , respectively, representing minimum rental income accrued on a straight-line basis to be paid by tenants over the remaining term of their respective leases. 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, 2018 and 2017, the Company had no assets designated as held for sale. 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, 2018 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 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 $10.3 million and $6.9 million , net of accumulated amortization of $7.3 million and $8.2 million at December 31, 2018 and 2017 , respectively, and are reflected as a reduction of the related debt in the Consolidated Balance Sheets. At December 31, 2017, deferred debt costs totaling $1.8 million , related to the Glebe Road construction loan, which had no outstanding balance, are included in Other Assets in the Consolidated Balance Sheets. 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. 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. 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, 2018 , 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 2018 , 2017 , and 2016 . The tax basis of the Company’s real estate investments was approximately $1.35 billion and $1.32 billion as of December 31, 2018 and 2017 , 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 2015. Stock Based Employee Compensation, Deferred Compensation and Stock Plan for Directors 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 in general and administrative expenses. The Company has a stock plan, which was originally approved in 2004, amended in 2008 and 2013 and which expires in 2023, for the purpose of attracting and retaining executive officers, directors and other key personnel (the "Stock Plan"). Pursuant to the Stock Plan, the Compensation Committee established a Deferred Compensation Plan for Directors for the benefit of its directors and their beneficiaries, which replaced a previous Deferred Compensation and Stock Plan for Directors. A director may make an annual election to defer all or part of his or her director’s fees and has the option to have the 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 the director elects to have fees paid in stock, fees earned during a calendar quarter are aggregated and divided by the common stock’s closing market price on the first trading day of the following quarter to determine the number of shares to be allocated to the director. As of December 31, 2018 , the directors’ deferred fee accounts comprise 114,644 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 Shareholders, and their issuance may not be deferred. Each director was issued 200 shares for each of the years ended December 31, 2018 , 2017 , and 2016 . The shares were valued at the closing stock price on the dates the shares were awarded and included in general and administrative expenses in the total amounts of $108,800 , $130,700 , and $150,100 , for the years ended December 31, 2018 , 2017 , and 2016 , respectively. Noncontrolling Interest Saul Centers is the sole general partner of the Operating Partnership, owning a 74.3% common interest as of December 31, 2018 . 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. 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) 2018 2017 2016 Weighted average common shares outstanding - Basic 22,383 21,901 21,505 Effect of dilutive options 42 107 110 Weighted average common shares outstanding - Diluted 22,425 22,008 21,615 Average share price $ 52.50 $ 61.63 $ 58.96 Non-dilutive options 492 — 129 Years non-dilutive options were issued 2015, 2016 and 2017 2007, 2015, and 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 May 2014, the FASB issued ASU No. 2014-09 titled “Revenue from Contracts with Customers” and subsequently issued several related ASUs (collectively “ASU 2014-09”). ASU 2014-09 replaces most existing revenue recognition guidance and requires an entity to recognize the amount of revenue which it expects to be entitled for the transfer of promised goods or services to customers. ASU 2014-09 is effective for annual periods beginning after December 15, 2017, and interim periods within those years and early adoption is not permitted. ASU 2014-09 must be applied retrospectively by either restating prior periods or by recognizing the cumulative effect as of the first date of application. The Company adopted ASU 2014-09 effective January 1, 2018, using the modified retrospective approach. The adoption of ASU 2014-09 did not have an impact on the consolidated financial statements because the majority of the Company’s revenue consists of lease-related income from leasing arrangements, which is specifically excluded from ASU 2014-09. Other revenues, as a whole, are immaterial to total revenues. There was no change to previously reported amounts as a result of the adoption of ASU 2014-09. In February 2016, the FASB issued 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 anticipate election of the practical expedient with respect to cost recoveries. We anticipate that the accounting for initial direct costs will impact the amount of those costs that are charged to expense. In 2018, we capitalized approximately $2.1 million of initial direct costs that would have been charged to expense under ASU 2016-02. For those leases where we are lessee, the adoption of ASU 2016-02 will require us to record a right of use asset and a lease liability on the consolidated balance sheet. The right of use asset and lease liability are not expected to be material to the financial statements. 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. We are evaluating the impact that ASU 2016-13 will have on our consolidated financial statements and related disclosures. In January 2017, the FASB issued ASU 2017-01, "Clarifying the Definition of a Business" ("ASU 2017-01"). ASU 2017-01 provides that when substantially all of the fair value of the gross assets acquired is concentrated in a single identifiable asset or group of similar identifiable assets, the set is not a business. ASU 2017-01 is effective prospectively for annual periods beginning after December 15, 2017, and interim periods within those years. Early application is permitted for transactions for which the acquisition date occurs before the effective date provided the transaction has not been reported in the financial statements. The Company adopted ASU 2017-01 during the first quarter of 2017, the effect of which, for asset acquisitions, was (a) the capitalization of acquisition costs, instead of expense, and (b) recordation of acquired assets and assumed liabilities at relative fair value, instead of fair value. Reclassifications Certain reclassifications have been made to prior years to conform to the presentation used for year ended December 31, 2018 .

Real Estate Acquired

Real Estate Acquired	12 Months Ended
	Dec. 31, 2018
Real Estate [Abstract]
Real Estate Acquired	REAL ESTATE ACQUIRED 700, 726, 730 and 750 N. Glebe Road In August 2014, the Company purchased for $40.0 million , 750 N. Glebe Road and incurred acquisition costs of $0.4 million . In December 2014, the Company purchased for $2.8 million 730 N. Glebe Road and incurred acquisition costs of $40,400 . In September 2015, the Company purchased for $4.0 million 726 N. Glebe Road and incurred acquisition costs of $0.1 million . In August 2016 , the Company purchased for $7.2 million , including acquisition costs, 700 N. Glebe Road . These properties are contiguous and are located in Arlington, Virginia. Thruway pad In August 2016 , the Company purchased for $3.1 million , a retail pad site with an occupied bank building in Winston Salem, North Carolina , and incurred acquisition costs of $60,400 . The property is contiguous with and an expansion of the Company's Thruway asset. Beacon Center In the fourth quarter of 2016, the Company purchased for $22.7 million , including acquisition costs, the land underlying Beacon Center. The land was previously leased by the Company with an annual rent of approximately $60,000 . The purchase price was funded in part by an $11.25 million increase to the existing mortgage collateralized by Beacon Center and in part by the Company’s revolving credit facility. Southdale In the fourth quarter of 2016, the Company purchased for $15.3 million , including acquisition costs, the land underlying Southdale. The land was previously leased by the Company with an annual rent of approximately $60,000 . The purchase price was funded by the Company’s revolving credit facility. 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. This site has mixed-use development potential of up to 325 apartment units and approximately 10,000 square feet of street level retail pursuant to the approved Bethesda Downtown Plan. 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 Company is evaluating concept plans for the combined property in order to increase the mixed-use development potential by up to 40 additional apartment units. The purchase price was funded through the Company's credit facility. 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. See Note 2. Summary of Significant Accounting Policies-Real Estate Investment Properties. 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. During 2016, the Company purchased properties that had an aggregate cost of $10.3 million , and incurred acquisition costs totaling $60,400 . The purchase price was allocated to the assets acquired and liabilities assumed based on their fair value as shown in the following table. (in thousands) 700 N. Glebe Road Thruway Pad Total Land $ 7,236 $ 2,196 $ 9,432 Buildings — 874 874 In-place Leases — 93 93 Above Market Rent — — — Below Market Rent — (63 ) (63 ) Total Purchase Price $ 7,236 $ 3,100 $ 10,336 The gross carrying amount of lease intangible assets included in deferred leasing costs as of December 31, 2018 and 2017 was $12.5 million and $12.3 million , respectively, and accumulated amortization was $8.1 million and $7.5 million , respectively. Amortization expense totaled $1.3 million , $1.1 million and $1.0 million , for the years ended December 31, 2018 , 2017 , and 2016 , respectively. The gross carrying amount of below market lease intangible liabilities included in deferred income as of December 31, 2018 and 2017 was $24.8 million and $25.1 million , respectively, and accumulated amortization was $13.1 million and $11.8 million , respectively. Accretion income totaled $1.7 million , $1.7 million , and $1.8 million , for the years ended December 31, 2018 , 2017 , and 2016 , respectively. The gross carrying amount of above market lease intangible assets included in accounts receivable as of December 31, 2018 and 2017 was $0.8 million and $0.6 million , respectively, and accumulated amortization was $0.1 million and $39,500 , respectively. Amortization expense totaled $110,500 , $31,600 and $1,500 , for the years ended December 31, 2018 , 2017 and 2016 , respectively. The remaining weighted-average amortization period as of December 31, 2018 is 4.1 years, 7.2 years, and 5.5 years for lease acquisition costs, above market leases and below market leases, respectively. As of December 31, 2018 , 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 2019 $ 1,141 $ 102 $ 1,533 2020 785 52 1,434 2021 538 36 1,409 2022 383 33 1,306 2023 316 33 1,297 Thereafter 1,197 376 4,731 Total $ 4,360 $ 632 $ 11,710

Noncontrolling Interests - Hold

Noncontrolling Interests - Holders of Convertible Limited Partnership Units in the Operating Partnership	12 Months Ended
	Dec. 31, 2018
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 The Saul Organization holds a 25.7% limited partnership interest in the Operating Partnership represented by 7,825,980 limited partnership units, as of December 31, 2018 . 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, 2018 , approximately 920,000 units were eligible for conversion. The impact of the Saul Organization’s 25.7% 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, 2018 , 2017 , and 2016 , were 30,156,100 , 29,510,900 , and 28,989,900 , respectively.

Mortgage Notes Payable, Revolvi

Mortgage Notes Payable, Revolving Credit Facility, Interest Expense and Amortization of Deferred Debt Costs	12 Months Ended
	Dec. 31, 2018
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, 2018 , the principal amount of outstanding debt totaled $1.0 billion , of which $910.2 million was fixed rate debt and $122.0 million was variable rate debt. The principal amount of the Company’s outstanding debt totaled $965.5 million at December 31, 2017 , of which $890.4 million was fixed rate debt and $75.1 million was variable rate debt. At December 31, 2018 , 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, 2018 , based on the value of the Company's unencumbered properties, approximately $190.7 million was available under the revolving credit facility, $47.0 million was outstanding and approximately $184,600 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, 2018 , 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 loan (approximately $10.0 million of the $69.7 million outstanding balance at December 31, 2018, which guarantee will be reduced to (i) $6.7 million on October 1, 2019, (ii) $3.3 million on October 1, 2020 and (iii) zero on October 1, 2021), (b) a portion of the Kentlands Square II mortgage loan (approximately $8.8 million of the $35.3 million outstanding balance at December 31, 2018) and (c) a portion of the Broadlands mortgage (approximately $4.0 million of the $31.9 million outstanding balance at December 31, 2018). All other notes payable are non-recourse. In November 2016, the existing loan secured by Beacon Center was increased by $11.25 million . The interest rate, amortization period and maturity date did not change; the required monthly payment was increased to $268,500 . Proceeds were used to partially fund the purchase of the ground which underlies Beacon Center. 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 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 Glebe Road 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. 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. The following is a summary of notes payable as of December 31, 2018 and 2017 . Notes Payable December 31, Interest Scheduled (Dollars in thousands) 2018 2017 Rate * Maturity * Fixed rate mortgages: $ — (a) $ 30,201 5.88 % Jan-2019 9,159 (b) 9,783 5.76 % May-2019 12,676 (c) 13,529 5.62 % Jul-2019 12,714 (d) 13,543 5.79 % Sep-2019 11,295 (e) 12,029 5.22 % Jan-2020 9,601 (f) 9,948 5.60 % May-2020 7,766 (g) 8,244 5.30 % Jun-2020 36,711 (h) 37,998 5.83 % Jul-2020 6,943 (i) 7,325 5.81 % Feb-2021 5,480 (j) 5,649 6.01 % Aug-2021 31,723 (k) 32,673 5.62 % Jun-2022 9,728 (l) 9,999 6.08 % Sep-2022 10,609 (m) 10,877 6.43 % Apr-2023 11,702 (n) 12,577 6.28 % Feb-2024 14,952 (o) 15,452 7.35 % Jun-2024 13,013 (p) 13,438 7.60 % Jun-2024 23,198 (q) 23,873 7.02 % Jul-2024 27,222 (r) 28,115 7.45 % Jul-2024 27,168 (s) 28,025 7.30 % Jan-2025 14,086 (t) 14,537 6.18 % Jan-2026 102,310 (u) 105,817 5.31 % Apr-2026 30,888 (v) 32,016 4.30 % Oct-2026 35,258 (w) 36,507 4.53 % Nov-2026 16,515 (x) 17,086 4.70 % Dec-2026 62,630 (y) 64,472 5.84 % May-2027 15,345 (z) 15,859 4.04 % Apr-2028 38,120 (aa) 39,968 3.51 % Jun-2028 15,547 (bb) 16,055 3.99 % Sep-2028 27,060 (cc) 27,884 3.69 % Mar-2030 14,526 (dd) 14,950 3.99 % Apr-2030 38,076 (ee) 39,140 3.39 % Feb-2032 69,691 (ff) 71,211 4.88 % Sep-2032 58,523 (gg) 60,000 3.75 % Dec-2032 31,941 (hh) — 4.41 % Nov-2033 22,900 (ii) — 4.69 % Jan-2034 11,781 (jj) 11,613 8.00 % Apr-2034 23,332 (kk) — 4.67 % Sep-2035 Total fixed rate 910,189 890,393 5.18 % 8.5 Years Variable rate loans: 47,000 (ll) 61,000 LIBOR + 1.35 % Jan-2022 75,000 (mm) — LIBOR + 1.30 % Jan-2023 — (nn) 14,135 LIBOR + 1.65 % Feb-2018 Total variable rate 122,000 75,135 3.84 % 3.7 Years Total notes payable $ 1,032,189 $ 965,528 5.02 % 8.0 Years * Interest rate and scheduled maturity data presented as of December 31, 2018 . Totals computed using weighted averages. Amounts shown are principal amounts and have not been reduced by any deferred debt issuance costs. (a) The loan was collateralized by three shopping centers, Broadlands Village, The Glen and Kentlands Square I, and required equal monthly principal and interest payments of $306,000 based upon a 25 -year amortization schedule and a final payment of $28.4 million at loan maturity. The loan was repaid in full in 2018 and replaced with two new loans. See (hh) and (ii) below. (b) The loan is collateralized by Olde Forte Village and requires equal monthly principal and interest payments of $98,000 based upon a 25 -year amortization schedule and a final payment of $9.0 million at loan maturity. Principal of $624,100 was amortized during 2018 . (c) The loan is collateralized by Countryside and requires equal monthly principal and interest payments of $133,000 based upon a 25 -year amortization schedule and a final payment of $12.3 million at loan maturity. Principal of $853,100 was amortized during 2018 . (d) The loan is collateralized by Briggs Chaney MarketPlace and requires equal monthly principal and interest payments of $133,000 based upon a 25 -year amortization schedule and a final payment of $12.2 million at loan maturity. Principal of $829,100 was amortized during 2018 . (e) The loan is collateralized by Shops at Monocacy and requires equal monthly principal and interest payments of $112,000 based upon a 25 -year amortization schedule and a final payment of $10.6 million at loan maturity. Principal of $733,800 was amortized during 2018 . (f) The loan is collateralized by Boca Valley Plaza and requires equal monthly principal and interest payments of $75,000 based upon a 30 -year amortization schedule and a final payment of $9.1 million at loan maturity. Principal of $347,300 was amortized during 2018 . (g) The loan is collateralized by Palm Springs Center and requires equal monthly principal and interest payments of $75,000 based upon a 25 -year amortization schedule and a final payment of $7.1 million at loan maturity. Principal of $477,900 was amortized during 2018 . (h) The loan and a corresponding interest-rate swap closed on June 29, 2010 and are collateralized by Thruway. On a combined basis, the loan and the interest-rate swap require equal monthly principal and interest payments of $289,000 based upon a 25 -year amortization schedule and a final payment of $34.8 million at loan maturity. Principal of $1.3 million was amortized during 2018 . (i) The loan is collateralized by Jamestown Place and requires equal monthly principal and interest payments of $66,000 based upon a 25 -year amortization schedule and a final payment of $6.1 million at loan maturity. Principal of $381,700 was amortized during 2018 . (j) The loan is collateralized by Hunt Club Corners and requires equal monthly principal and interest payments of $42,000 based upon a 30 -year amortization schedule and a final payment of $5.0 million , at loan maturity. Principal of $169,300 was amortized during 2018 . (k) The loan is collateralized by Lansdowne Town Center and requires monthly principal and interest payments of $230,000 based on a 30 -year amortization schedule and a final payment of $28.2 million at loan maturity. Principal of $949,600 was amortized during 2018 . (l) The loan is collateralized by Orchard Park and requires equal monthly principal and interest payments of $73,000 based upon a 30 -year amortization schedule and a final payment of $8.6 million at loan maturity. Principal of $270,300 was amortized during 2018 . (m) The loan is collateralized by BJ’s Wholesale and requires equal monthly principal and interest payments of $80,000 based upon a 30 -year amortization schedule and a final payment of $9.3 million at loan maturity. Principal of $268,400 was amortized during 2018 . (n) The loan is collateralized by Great Falls shopping center. The loan consists of three notes which require equal monthly principal and interest payments of $138,000 based upon a weighted average 26 -year amortization schedule and a final payment of $6.3 million at maturity. Principal of $874,800 was amortized during 2018 . (o) The loan is collateralized by Leesburg Pike and requires equal monthly principal and interest payments of $135,000 based upon a 25 -year amortization schedule and a final payment of $11.5 million at loan maturity. Principal of $499,800 was amortized during 2018 . (p) The loan is collateralized by Village Center and requires equal monthly principal and interest payments of $119,000 based upon a 25 -year amortization schedule and a final payment of $10.1 million at loan maturity. Principal of $424,700 was amortized during 2018 . (q) The loan is collateralized by White Oak and requires equal monthly principal and interest payments of $193,000 based upon a 24.4 year weighted amortization schedule and a final payment of $18.5 million at loan maturity. The loan was previously collateralized by Van Ness Square. During 2012, the Company substituted White Oak as the collateral and borrowed an additional $10.5 million . Principal of $675,200 was amortized during 2018 . (r) The loan is collateralized by Avenel Business Park and requires equal monthly principal and interest payments of $246,000 based upon a 25 -year amortization schedule and a final payment of $20.9 million at loan maturity. Principal of $893,200 was amortized during 2018 . (s) The loan is collateralized by Ashburn Village and requires equal monthly principal and interest payments of $240,000 based upon a 25 -year amortization schedule and a final payment of $20.5 million at loan maturity. Principal of $857,000 was amortized during 2018 . (t) The loan is collateralized by Ravenwood and requires equal monthly principal and interest payments of $111,000 based upon a 25 -year amortization schedule and a final payment of $10.1 million at loan maturity. Principal of $451,200 was amortized during 2018 . (u) The loan is collateralized by Clarendon Center and requires equal monthly principal and interest payments of $753,000 based upon a 25 -year amortization schedule and a final payment of $70.5 million at loan maturity. Principal of $3.5 million was amortized during 2018 . (v) The loan is collateralized by Severna Park MarketPlace and requires equal monthly principal and interest payments of $207,000 based upon a 25 -year amortization schedule and a final payment of $20.3 million at loan maturity. Principal of $1.1 million was amortized during 2018 . (w) The loan is collateralized by Kentlands Square II and requires equal monthly principal and interest payments of $240,000 based upon a 25 -year amortization schedule and a final payment of $23.1 million at loan maturity. Principal of $1.2 million was amortized during 2018 . (x) The loan is collateralized by Cranberry Square and requires equal monthly principal and interest payments of $113,000 based upon a 25 -year amortization schedule and a final payment of $10.9 million at loan maturity. Principal of $570,500 was amortized during 2018 . (y) The loan in the original amount of $73.0 million closed in May 2012, is collateralized by Seven Corners and requires equal monthly principal and interest payments of $463,200 based upon a 25 -year amortization schedule and a final payment of $42.3 million at loan maturity. Principal of $1.8 million was amortized during 2018 . (z) The loan is collateralized by Hampshire Langley and requires equal monthly principal and interest payments of $95,400 based upon a 25 -year amortization schedule and a final payment of $9.5 million at loan maturity. Principal of $513,700 was amortized in 2018 . (aa) The loan is collateralized by Beacon Center and requires equal monthly principal and interest payments of $268,500 based upon a 20 -year amortization schedule and a final payment of $17.1 million at loan maturity. Principal of $1.8 million was amortized in 2018 . (bb) The loan is collateralized by Seabreeze Plaza and requires equal monthly principal and interest payments of $94,900 based upon a 25 -year amortization schedule and a final payment of $9.5 million at loan maturity. Principal of $507,600 was amortized in 2018 . (cc) The loan is collateralized by Shops at Fairfax and Boulevard shopping centers and requires equal monthly principal and interest payments totaling $153,300 based upon a 25 -year amortization schedule and a final payment of $15.5 million at maturity. Principal of $824,000 was amortized in 2018 . (dd) The loan is collateralized by Northrock and requires equal monthly principal and interest payments totaling $84,400 based upon a 25 -year amortization schedule and a final payment of $8.4 million at maturity. Principal of $423,600 was amortized in 2018 . (ee) The loan is collateralized by Burtonsville Town Square and requires equal monthly principal and interest payments of $197,900 based on a 25 -year amortization schedule and a final payment of $20.3 million at loan maturity. Principal of $1.1 million was amortized in 2018 . (ff) The loan is a $71.6 million construction-to-permanent facility that is collateralized by and financed a portion of the construction costs of Park Van Ness. During the construction period, interest was funded by the loan. Effective September 1, 2017, the loan converted to permanent financing and requires monthly principal and interest payments totaling $413,500 based upon a 25 -year amortization schedule. A final payment of $39.6 million will be due at maturity. Principal of $1.5 million was amortized in 2018 . (gg) The loan is collateralized by Washington Square and requires equal monthly principal and interest payments of $308,500 based upon a 25 -year amortization schedule and a final payment of $31.1 million at loan maturity. Principal of $1.5 million was amortized in 2018 . (hh) The loan is collateralized by Broadlands Village and requires equal monthly principal and interest payments of $176,200 based on a 25 -year amortization schedule and a final payment of $17.3 million at loan maturity. Principal of $58,600 was amortized in 2018 . (ii) The loan is collateralized by The Glen and requires equal monthly principal and interest payments of $129,800 based on a 25 -year amortization schedule and a final payment of $12.5 million at loan maturity. (jj) The Company entered into a sale-leaseback transaction with its Olney property and is accounting for that transaction as a secured financing. The arrangement requires monthly payments of $60,400 which increase by 1.5% on May 1, 2015, and every May 1 thereafter. The arrangement provides for a final payment of $14.7 million and has an implicit interest rate of 8.0% . Negative amortization in 2018 totaled $168,600 . (kk) The loan is a $157.0 million construction-to-permanent facility that is collateralized by and will finance a portion of the construction costs of Glebe Road. During the construction period, interest will be funded by the loan. After conversion to a permanent loan, monthly principal and interest payments totaling $887,900 will be required based upon a 25 -year amortization schedule. (ll) The loan is a $325.0 million unsecured revolving credit facility. Interest accrues at a rate equal to the sum of one-month LIBOR plus a spread of 135 basis points. The line may be extended at the Company’s option for one year with payment of a fee of 0.15% . Monthly payments, if required, are interest only and vary depending upon the amount outstanding and the applicable interest rate for any given month. (mm) The loan is a $75.0 million unsecured term facility. Interest accrues at a rate equal to the sum of one-month LIBOR plus a spread of 130 basis points. Monthly payments are interest only. (nn) The loan was collateralized by Metro Pike Center and requires monthly principal and interest payments of approximately $48,000 and a final payment of $14.2 million at loan maturity. The loan was repaid in full during 2018 . The carrying value of the properties collateralizing the mortgage notes payable totaled $1.1 billion and $1.0 billion , as of December 31, 2018 and 2017 , 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, 2018 . • 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 each of December 31, 2018 and 2017 , totaling $51.0 million , are guaranteed by members of the Saul Organization. As of December 31, 2018 , 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 2019 $ 60,794 $ 2,257 $ 63,051 2020 61,163 28,042 89,205 2021 11,012 27,815 38,827 2022 83,502 (a) 28,381 111,883 2023 84,225 28,745 112,970 Thereafter 480,132 136,121 616,253 Principal amount $ 780,828 $ 251,361 1,032,189 Unamortized deferred debt costs 10,343 Net $ 1,021,846 (a) Includes $47.0 million outstanding under the revolving facility. The components of interest expense are set forth below. (in thousands) Year ended December 31, 2018 2017 2016 Interest incurred $ 49,652 $ 49,322 $ 46,867 Amortization of deferred debt costs 1,610 1,392 1,343 Capitalized interest (6,222 ) (3,489 ) (2,527 ) Total $ 45,040 $ 47,225 $ 45,683 Deferred debt costs capitalized during the years ending December 31, 2018 , 2017 and 2016 totaled $3.2 million , $2.6 million and $0.1 million , respectively.

Lease Agreements

Lease Agreements	12 Months Ended
	Dec. 31, 2018
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, 2018 , 2017 , and 2016 , amounted to $184.7 million , $181.1 million , and $172.4 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) 2019 $ 163,489 2020 146,425 2021 125,372 2022 101,778 2023 79,903 Thereafter 244,801 $ 861,768 The majority of the leases provide for rental increases and expense recoveries based on fixed annual increases or increases in the Consumer Price Index and 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, 2018 , 2017 , and 2016 , amounted to $35.5 million , $35.3 million , and $34.3 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 $1.0 million , $1.5 million , and $1.4 million , for the years ended December 31, 2018 , 2017 , and 2016 , respectively.

Long-Term Lease Obligations

Long-Term Lease Obligations	12 Months Ended
	Dec. 31, 2018
Leases [Abstract]
Long-Term Lease Obligations	LONG-TERM LEASE OBLIGATIONS During 2016 and 2017, the Company purchased the land underlying Olney, Beacon Center and Southdale - See Note 3. As a result, at December 31, 2018, no properties are subject to noncancelable long-term leases which apply to underlying land. Reflected in the accompanying consolidated financial statements is minimum ground rent expense of $10,500 and $159,000 , for the years ended December 31, 2017 and 2016 , respectively. 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, 2018 , 2017 , and 2016 was $779,800 , $774,700 , and $843,300 , 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, 2018
Noncontrolling Interest [Abstract]
Equity and Noncontrolling Interest	EQUITY AND NONCONTROLLING INTEREST The Consolidated Statements of Operations for the years ended December 31, 2018 , 2017 , and 2016 reflect noncontrolling interest of $12.5 million , $12.4 million , and $11.4 million , respectively, representing the Saul Organization’s share of the net income for the year. On January 23, 2018 , Saul Centers sold, in an underwritten public offering, 3.0 million depositary shares, each representing 1/100 th of a share of 6.125% Series D Cumulative Redeemable Preferred Stock (the "Series D Stock"), providing net cash proceeds of approximately $72.6 million . 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 February 22, 2018, the proceeds from the offering, together with cash on hand, were used to redeem 3.0 million depositary shares, each representing 1/100th of a share of the Company’s 6.875% Series C Cumulative Redeemable Preferred Stock (the “Series C Stock”). Costs associated with the redemption were charged against Net income available to common stockholders. At December 31, 2018, the Company had outstanding, 4.2 million depositary shares, each representing 1/100 th of a share of 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.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2018
Related Party Transactions [Abstract]
Related Party Transactions	RELATED PARTY TRANSACTIONS The Chairman and Chief Executive Officer, the President and Chief Operating Officer, 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 $345,900 , $349,500 , and $329,000 , for 2018 , 2017 , and 2016 , 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, 2018 , 2017 , and 2016 , the Company contributed three times the amount deferred by employees. The Company’s expense, included in general and administrative expense, totaled $282,500 , $228,500 , and $250,800 , for the years ended December 31, 2018 , 2017 , and 2016 , respectively. All amounts deferred by employees and the Company are fully vested. The cumulative unfunded liability under this plan was $2.7 million and $2.4 million , at December 31, 2018 and 2017 , 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, 2018 , 2017 , and 2016 , which included rental expense for the Company’s headquarters lease (see Note 7. Long Term Lease Obligations), totaled $8.4 million , $8.1 million , and $7.2 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, 2018 and 2017 , accounts payable, accrued expenses and other liabilities included $933,400 and $993,200 , 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. 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 $407,900 , $288,400 , and $360,500 , for the years ended December 31, 2018 , 2017 , and 2016 , 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, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock Option Plan	STOCK OPTION PLAN The Company established a stock option plan in 1993 (the “1993 Plan”) for the purpose of attracting and retaining executive officers and other key personnel. The 1993 Plan provides for grants of options to purchase up to 400,000 shares of common stock. The 1993 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. 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 and further amended at the 2013 Annual Meeting (the “Amended 2004 Plan”). The Amended 2004 Plan, which terminates in 2023, provides for grants of options to purchase up to 2,000,000 shares of common stock as well as grants of up to 200,000 shares of common stock to directors. 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 April 24, 2009 , the Compensation Committee granted options to purchase 32,500 shares (all nonqualified stock options) to 13 Company directors (the “2009 Options”), which were immediately exercisable and expire on April 23, 2019 . The exercise price of $32.68 per share was the closing market price of the Company’s common stock on the date of the award. Using the Black-Scholes model, the Company determined the total fair value of the 2009 Options to be $222,950 . Because the directors’ options vested immediately, the entire $222,950 was expensed as of the date of grant. No options were granted to the Company’s officers in 2009. Effective May 7, 2010 , the Compensation Committee granted options to purchase 32,500 shares (all nonqualified stock options) to 13 Company directors (the “2010 Options”), which were immediately exercisable and expire on May 6, 2020 . The exercise price of $38.76 per share was the closing market price of the Company’s common stock on the date of the award. Using the Black-Scholes model, the Company determined the total fair value of the 2010 Options to be $287,950 . Because the directors’ options vested immediately, the entire $287,950 was expensed as of the date of grant. No options were granted to the Company’s officers in 2010. Effective May 13, 2011 , the Compensation Committee granted options to purchase 195,000 shares ( 65,300 incentive stock options and 129,700 nonqualified stock options) to 15 Company officers and 13 Company Directors (the “2011 options”), which expire on May 12, 2021 . The officers’ 2011 Options vest 25% per year over four years and are subject to early expiration upon termination of employment. The directors’ 2011 options were immediately exercisable. The exercise price of $41.82 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 2011 Options to be $1.6 million , of which $1.3 million and $297,375 were assigned to the officer options and director options, respectively. Because the directors’ options vested immediately, the entire $297,375 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 4, 2012 , the Compensation Committee granted options to purchase 277,500 shares ( 26,157 incentive stock options and 251,343 nonqualified stock options) to 15 Company officers and 14 Company Directors (the “2012 options”), which expire on May 3, 2022 . The officers’ 2012 Options vest 25% per year over four years and are subject to early expiration upon termination of employment. The directors’ 2012 Options were immediately exercisable. The exercise price of $39.29 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 2012 Options to be $1.7 million , of which $1.4 million and $257,250 were assigned to the officer options and director options, respectively. Because the directors’ options vested immediately, the entire $257,250 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 10, 2013 , the Compensation Committee granted options to purchase 237,500 shares ( 35,592 incentive stock options and 201,908 nonqualified stock options) to 15 Company officers and 14 Company Directors (the "2013 options"), which expire on May 9, 2023 . The officers' 2013 Options vest 25% per year over four years and are subject to early expiration upon termination of employment. The directors' 2013 options were immediately exercisable. The exercise price of $44.42 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 2013 Options to be $1.5 million , of which $1.2 million and $278,250 were assigned to the officer options and director options, respectively. Because the directors' options vested immediately, the entire $278,250 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 option was vested. Effective May 9, 2014 , the Compensation Committee granted options to purchase 200,000 shares ( 29,300 incentive stock options and 170,700 nonqualified stock options) to 18 Company officers and 12 Company Directors (the “2014 options”), which expire on May 8, 2024 . The officers’ 2014 Options vest 25% per year over four years and are subject to early expiration upon termination of employment. The directors’ 2014 Options were immediately exercisable. The exercise price of $47.03 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 2014 Options to be $1.3 million , of which $1.2 million and $109,500 were assigned to the officer options and director options, respectively. Because the directors’ options vested immediately, the entire $109,500 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 8, 2015 , the Compensation Committee granted options to purchase 225,000 shares ( 33,690 incentive stock options and 191,310 nonqualified stock options) to 19 Company officers and 14 Company Directors (the “2015 options”), which expire on May 7, 2025 . The officers’ 2015 Options vest 25% per year over four years and are subject to early expiration upon termination of employment. The directors’ 2015 Options were immediately exercisable. The exercise price of $51.07 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 2015 Options to be $1.57 million , of which $1.44 million and $125,300 were assigned to the officer options and director options, respectively. Because the directors’ options vested immediately, the entire $125,300 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 6, 2016 , the Compensation Committee granted options to purchase 226,500 shares ( 24,248 incentive stock options and 202,252 nonqualified stock options) to 19 Company officers and 13 Company Directors (the “2016 options”), which expire on May 5, 2026 . The officers’ 2016 Options vest 25% per year over four years and are subject to early expiration upon termination of employment. The directors’ 2016 Options were immediately exercisable. The exercise price of $57.74 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 2016 Options to be $1.2 million , of which $1.0 million and $151,100 were assigned to the officer options and director options, respectively. Because the directors’ options vested immediately, the entire $151,100 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 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. The following table summarizes the amount and activity of each grant, the total value and variables used in the computation and the amount expensed and included in general and administrative expense in the Consolidated Statements of Operations for the years ended December 31, 2018 , 2017 and 2016 . SAUL CENTERS, INC. (Dollars in thousands, except per share data) Stock options issued Directors Grant date 4/24/2009 5/7/2010 5/13/2011 5/4/2012 5/10/2013 5/9/2014 5/8/2015 5/6/2016 5/5/2017 5/11/2018 Subtotals Total grant 32,500 32,500 32,500 35,000 35,000 30,000 35,000 32,500 27,500 27,500 320,000 Vested 32,500 32,500 32,500 35,000 35,000 30,000 35,000 32,500 27,500 27,500 320,000 Exercised 30,000 27,500 25,000 25,000 22,500 17,500 12,500 7,500 — 2,500 170,000 Forfeited — 2,500 2,500 — — — — — 2,500 — 7,500 Exercisable at December 31, 2018 2,500 2,500 5,000 10,000 12,500 12,500 22,500 25,000 25,000 25,000 142,500 Remaining unexercised 2,500 2,500 5,000 10,000 12,500 12,500 22,500 25,000 25,000 25,000 142,500 Exercise price $ 32.68 $ 38.76 $ 41.82 $ 39.29 $ 44.42 $ 47.03 $ 51.07 $ 57.74 $ 59.41 $ 49.46 Volatility 0.344 0.369 0.358 0.348 0.333 0.173 0.166 0.166 0.173 0.192 Expected life (years) 6.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 Assumed yield 4.54 % 4.23 % 4.16 % 4.61 % 4.53 % 4.48 % 4.54 % 3.75 % 3.45 % 3.70 % Risk-free rate 2.19 % 2.17 % 1.86 % 0.78 % 0.82 % 1.63 % 1.50 % 1.23 % 1.89 % 2.84 % Total value at grant date $ 223 $ 288 $ 298 $ 257 $ 278 $ 110 $ 125 $ 151 $ 166 $ 169 $ 2,065 Expensed in previous years 223 288 298 257 278 110 125 — — — 1,579 Expensed in 2016 — — — — — — — 151 — — 151 Expensed in 2017 — — — — — — — — 166 — 166 Expensed in 2018 — — — — — — — — — 169 169 Future expense — — — — — — — — — — — Officers Grant date 5/13/2011 5/4/2012 5/10/2013 5/9/2014 5/8/2015 5/6/2016 5/5/2017 5/11/2018 Subtotals Grand Totals Total grant 162,500 242,500 202,500 170,000 190,000 194,000 205,000 217,500 1,584,000 1,904,000 Vested 118,750 107,500 171,875 168,125 140,625 96,375 51,250 — 854,500 1,174,500 Exercised 103,750 92,455 129,375 46,126 20,625 3,750 — — 396,081 566,081 Forfeited 43,750 135,000 30,625 1,875 3,125 1,875 — — 216,250 223,750 Exercisable at December 31, 2018 15,000 15,045 42,500 121,999 120,000 92,625 51,250 — 458,419 600,919 Remaining unexercised 15,000 15,045 42,500 121,999 166,250 188,375 205,000 217,500 971,669 1,114,169 Exercise price $ 41.82 $ 39.29 $ 44.42 $ 47.03 $ 51.07 $ 57.74 $ 59.41 $ 49.46 Volatility 0.330 0.315 0.304 0.306 0.298 0.185 0.170 0.177 Expected life (years) 8.0 8.0 8.0 7.0 7.0 7.0 7.0 7.0 Assumed yield 4.81 % 5.28 % 5.12 % 4.89 % 4.94 % 3.80 % 3.50 % 3.75 % Risk-free rate 2.75 % 1.49 % 1.49 % 2.17 % 1.89 % 1.55 % 2.17 % 2.94 % Gross value at grant date $ 1,367 $ 1,518 $ 1,401 $ 1,350 $ 1,585 $ 1,137 $ 1,324 $ 1,313 $ 10,995 $ 13,060 Estimated forfeitures 368 845 212 15 142 86 92 83 1,843 1,843 Expensed in previous years 999 576 762 492 240 — — — 3,069 4,648 Expensed in 2016 — 97 269 296 360 175 — — 1,197 1,348 Expensed in 2017 — — 158 295 361 263 205 — 1,282 1,448 Expensed in 2018 — — — 252 361 263 308 205 1,389 1,558 Future expense — — — — 121 350 719 1,025 2,215 2,215 Weighted average term of remaining future expense 2.5 years The table below summarizes the option activity for the years 2018 , 2017 , and 2016 : 2018 2017 2016 Shares Weighted Shares Weighted Shares Weighted Outstanding at January 1 913,320 $ 52.80 833,630 $ 49.92 860,274 $ 46.58 Granted 245,000 49.46 232,500 59.41 226,500 57.74 Exercised (39,151 ) 42.98 (149,060 ) 46.97 (246,894 ) 45.59 Expired/Forfeited (5,000 ) 54.78 (3,750 ) 53.73 (6,250 ) 45.31 Outstanding December 31 1,114,169 52.40 913,320 52.80 833,630 49.92 Exercisable at December 31 600,919 50.93 430,945 48.94 375,255 46.68 The intrinsic value of options exercised in 2018 , 2017 , and 2016 , was $0.5 million , $2.2 million and $3.4 million , respectively. The intrinsic value of options outstanding and exercisable at year end 2018 was $0.5 million and $0.5 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, 2018, the final trading day of calendar 2018 , the closing price of $47.22 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, 2018 are 6.2 and 7.2 years, respectively.

Fair Value of Financial Instrum

Fair Value of Financial Instruments	12 Months Ended
	Dec. 31, 2018
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 4.40% and 3.90% , would be approximately $927.0 million and $951.7 million as of December 31, 2018 and 2017 , respectively, compared to the principal balance of $910.2 million and $890.4 million at December 31, 2018 and 2017 , respectively. A change in any of the significant inputs may lead to a change in the Company’s fair value measurement of its debt. Effective June 30, 2011, the Company determined that one of its interest-rate swap arrangements was a highly effective hedge of the cash flows under one of its variable-rate mortgage loans and designated the swap as a cash flow hedge of that mortgage. The swap is carried at fair value with changes in fair value recognized either in income or comprehensive income depending on the effectiveness of the swap. The following chart summarizes the changes in fair value of the Company’s swap for the indicated periods. (Dollars in thousands) Year ended December 31, 2018 2017 2016 Increase (decrease) in fair value: Recognized in earnings $ (3 ) $ 70 $ (6 ) Recognized in other comprehensive income 594 812 678 Total $ 591 $ 882 $ 672 The Company carries its interest rate swaps at fair value. The Company has determined the majority of the inputs used to value its derivative fall within Level 2 of the fair value hierarchy with the exception of the impact of counter-party risk, which was determined using Level 3 inputs and are not significant. Derivative instruments are classified within Level 2 of the fair value hierarchy because their values are determined using third-party pricing models which contain inputs that are derived from observable market data. Where possible, the values produced by the pricing models are verified by the market prices. Valuation models require a variety of inputs, including contractual terms, market prices, yield curves, credit spreads, measure of volatility, and correlations of such inputs. The swap agreement terminates on July 1, 2020 . As of December 31, 2018 , the fair value of the interest-rate swap was approximately $0.4 million and is included in “Accounts payable, accrued expenses and other liabilities” in the consolidated balance sheets. The decrease in value from inception of the swap designated as a cash flow hedge is reflected in “Other Comprehensive Income” in the Consolidated Statements of Comprehensive Income.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2018
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, 2018
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 $2.08 per share in 2018 , $2.04 per share in 2017 , and $1.84 per share in 2016 , Series C preferred stock dividends of $1.72 per depositary share during each of 2018 , 2017 , and 2016 , and Series D preferred stock dividends of $1.05 per depositary share in 2018 . Of the common stock dividends paid, $1.61 per share, $1.70 per share, and $1.75 per share, represented ordinary dividend income in 2018 , 2017 , and 2016 , respectively, and $0.47 , per share $0.34 per share and $0.09 per share represented return of capital to the shareholders in 2018, 2017, and 2016, respectively. All of the preferred stock dividends paid were considered ordinary dividend income. The following summarizes distributions paid during the years ended December 31, 2018 , 2017 , and 2016 , 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 2018 October 31 $ 2,953 $ 11,706 $ 4,062 216,476 $ 49.34 13,867 $ 50.20 July 31 2,953 11,590 4,055 201,500 51.68 13,107 52.60 April 30 2,672 11,545 3,942 85,202 47.54 42,422 47.83 January 31 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 October 31 $ 3,094 $ 11,221 $ 3,838 82,991 $ 59.33 15,596 $ 60.08 July 31 3,094 11,160 3,830 85,731 57.40 16,021 58.13 April 30 3,094 11,119 3,810 51,003 59.64 40,623 59.96 January 31 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 Distributions during 2016 October 31 $ 3,094 $ 10,168 $ 3,478 44,176 $ 57.18 30,891 $ 57.18 July 31 3,094 10,133 3,465 39,487 65.64 26,897 65.64 April 30 3,094 10,029 3,449 48,854 51.59 34,201 51.59 January 31 3,093 9,142 3,141 54,280 49.24 32,769 49.24 Total 2016 $ 12,375 $ 39,472 $ 13,533 186,797 124,758 In December 2018 , the Board of Directors of the Company authorized a distribution of $0.53 per common share payable in January 2019, to holders of record on January 17, 2019 . As a result, $12.0 million was paid to common shareholders on January 31, 2019 . Also, $4.1 million was paid to limited partnership unitholders on January 31, 2019 ( $0.53 per Operating Partnership unit). The Board of Directors authorized preferred stock dividends of (a) $0.4297 per Series C depositary share and (b) $0.3828 per Series D depositary share to holders of record on January 2, 2019 . As a result, $3.0 million was paid to preferred shareholders on January 15, 2019 . 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, 2018
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 2018 and 2017 . (In thousands, except per share amounts) 2018 1st Quarter 2nd Quarter 3rd Quarter 4th Quarter Total revenue $ 56,496 $ 56,293 $ 57,059 $ 58,328 Operating income before loss on early extinguishment of debt, gain on casualty settlement, and noncontrolling interests 14,946 15,405 16,692 15,510 Gain on sales of properties — 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 (In thousands, except per share amounts) 2017 1st Quarter 2nd Quarter 3rd Quarter 4th Quarter Total revenue $ 58,466 $ 55,907 $ 56,237 $ 56,675 Operating income before loss on early extinguishment of debt, gain on casualty settlement, and noncontrolling interests 17,374 14,422 14,386 14,416 Gain on sales of properties — — — — Net income attributable to Saul Centers, Inc. 13,704 11,510 11,483 11,560 Net income available to common stockholders 10,610 8,416 8,390 8,466 Net income available to common stockholders per diluted share 0.49 0.38 0.38 0.38

Business Segments

Business Segments	12 Months Ended
	Dec. 31, 2018
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 2018 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, 2018 Centers Properties and Other Totals Real estate rental operations: Revenue $ 164,671 $ 63,233 $ — $ 227,904 Expenses (34,970 ) (21,293 ) — (56,263 ) Income from real estate 129,701 41,940 — 171,641 Other revenue — — 272 272 Interest expense and amortization of deferred debt costs — — (45,040 ) (45,040 ) 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 $ 165,853 $ 61,352 $ — $ 227,205 Expenses (34,675 ) (20,917 ) — (55,592 ) Income from real estate 131,178 40,435 — 171,613 Other revenue — — 80 80 Interest expense and amortization of deferred debt costs — — (47,225 ) (47,225 ) 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 As of or for the year ended December 31, 2016 Real estate rental operations: Revenue $ 160,179 $ 56,840 $ — $ 217,019 Expenses (34,931 ) (18,770 ) — (53,701 ) Income from real estate 125,248 38,070 — 163,318 Other revenue — — 51 51 Interest expense and amortization of deferred debt costs — — (45,683 ) (45,683 ) General and administrative — — (17,496 ) (17,496 ) Depreciation and amortization of deferred leasing costs (29,964 ) (14,453 ) — (44,417 ) Acquisition related costs (60 ) — — (60 ) Change in fair value of derivatives — — (6 ) (6 ) Gain on sale of property — 1,013 — 1,013 Net income (loss) $ 95,224 $ 24,630 $ (63,134 ) $ 56,720 Capital investment $ 64,044 $ 27,001 $ — $ 91,045 Total assets $ 976,545 $ 358,419 $ 8,061 $ 1,343,025

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2018
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events The Company has reviewed operating activities for the period subsequent to December 31, 2018 and prior to the date that financial statements are issued, February 26, 2019 , 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, 2018
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, 2018 (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 Ashburn Village, Ashburn, VA $ 11,431 $ 20,391 $ 6,764 $ 24,957 $ 101 $ 31,822 $ 13,437 $ 18,385 $ 27,167 1994 & 2000-6 3/94 40 Ashland Square Phase I, Dumfries, VA 1,178 7,508 1,178 5,297 2,211 8,686 1,991 6,695 — 2007, 2013 12/04 20 & 50 Beacon Center, Alexandria, VA 24,161 18,466 22,674 19,934 19 42,627 14,814 27,813 38,120 1960 & 1974 1/72, 11/16 40 & 50 BJ’s Wholesale Club, Alexandria, VA 22,623 — 22,623 — — 22,623 — 22,623 10,609 3/08 — Boca Valley Plaza, Boca Raton, FL 16,720 1,756 5,735 12,741 — 18,476 4,837 13,639 9,601 2/04 40 Boulevard, Fairfax, VA 4,883 4,676 3,687 5,872 — 9,559 3,023 6,536 16,236 1969, 1999 & 2009 4/94 40 Briggs Chaney MarketPlace, Silver Spring, MD 27,037 4,169 9,789 21,417 — 31,206 8,606 22,600 12,714 4/04 40 Broadlands Village, Ashburn, VA 5,316 29,223 5,300 29,226 13 34,539 11,929 22,610 31,941 2003, 2004 & 2006 3/02 40 & 50 Burtonsville Town Square, Burtonsville, MD 74,212 4,800 28,401 49,472 1,139 79,012 2,324 76,688 38,076 2010 1/17 20 & 45 Countryside Marketplace, Sterling, VA 28,912 3,811 7,666 25,045 12 32,723 9,666 23,057 12,676 2/04 40 Cranberry Square, Westminster, MD 31,578 640 6,700 25,518 — 32,218 4,802 27,416 16,515 9/11 40 Cruse MarketPlace, Cumming, GA 12,226 521 3,901 8,846 — 12,747 3,335 9,412 — 3/04 40 Flagship Center, Rockville, MD 160 9 169 — — 169 — 169 — 1972 1/72 — French Market, Oklahoma City, OK 5,781 14,174 1,118 18,834 3 19,955 11,846 8,109 — 1972 & 1998 3/74 50 Germantown, Germantown, MD 2,034 567 2,034 567 — 2,601 353 2,248 — 1990 8/93 40 The Glen, Woodbridge, VA 12,918 8,192 5,300 15,810 — 21,110 9,582 11,528 22,900 1993 & 2005 6/94 40 Great Falls Center, Great Falls, VA 41,750 3,192 14,766 30,174 2 44,942 8,612 36,330 11,702 3/08 40 Hampshire Langley, Takoma, MD 3,159 3,527 1,856 4,635 195 6,686 3,805 2,881 15,345 1960 1/72 40 Hunt Club Corners, Apopka, FL 12,584 4,226 4,822 11,988 — 16,810 4,299 12,511 5,480 6/06, 12/12 40 Jamestown Place, Altamonte Springs, FL 14,055 1,861 4,455 11,461 — 15,916 3,848 12,068 6,943 11/05 40 Kentlands Square I, Gaithersburg, MD 14,379 665 5,006 9,701 337 15,044 3,966 11,078 — 2002 9/02 40 Kentlands Square II, Gaithersburg, MD 76,723 1,628 22,800 55,184 367 78,351 10,651 67,700 35,258 9/11, 9/13 40 Kentlands Place, Gaithersburg, MD 1,425 7,298 1,425 7,298 — 8,723 3,988 4,735 — 2005 1/04 50 Lansdowne Town Center, Leesburg, VA 6,545 38,528 6,546 37,702 825 45,073 15,011 30,062 31,723 2006 11/02 50 Leesburg Pike Plaza, Baileys Crossroads, VA 2,418 6,262 1,132 7,548 — 8,680 6,054 2,626 14,952 1965 2/66 40 Lumberton Plaza, Lumberton, NJ 4,400 11,305 950 14,754 1 15,705 13,062 2,643 — 1975 12/75 40 Metro Pike Center, Rockville, MD 33,123 4,235 26,064 7,411 3,883 37,358 1,587 35,771 — 12/10 40 Shops at Monocacy, Frederick, MD 9,541 13,957 9,260 14,238 — 23,498 5,999 17,499 11,295 2004 11/03 50 Northrock, Warrenton, VA 12,686 15,414 12,686 15,408 6 28,100 4,406 23,694 14,526 2009 01/08 50 Olde Forte Village, Ft. Washington, MD 15,933 6,669 5,409 17,193 — 22,602 7,672 14,930 9,159 2004 07/03 40 Olney, Olney, MD 4,963 2,106 3,079 3,990 — 7,069 3,390 3,679 11,781 1972 11/75 40 Orchard Park, Dunwoody, GA 19,377 1,029 7,751 12,655 — 20,406 3,802 16,604 9,728 7/07 40 Palm Springs Center, Altamonte Springs, FL 18,365 1,938 5,739 14,564 — 20,303 5,088 15,215 7,766 3/05 40 Ravenwood, Baltimore, MD 1,245 4,193 703 4,735 — 5,438 3,171 2,267 14,086 1959 & 2006 1/72 40 11503 Rockville Pike/5541 Nicholson Lane, Rockville, MD 26,561 24 22,113 4,472 — 26,585 918 25,667 — 10/10 40 1500/1580/1582/1584 Rockville Pike, Rockville, MD 51,149 2,238 43,863 7,483 2,041 53,387 6,121 47,266 — 12/12, 1/14, 4/14, 12/14 5, 10, 5, 4 Seabreeze Plaza, Palm Harbor, FL 24,526 2,315 8,665 18,176 — 26,841 6,169 20,672 15,547 11/05 40 Market Place at Sea Colony, Bethany Beach, DE 2,920 209 1,147 1,982 — 3,129 556 2,573 — 3/08 40 Seven Corners, Falls Church, VA 4,848 44,101 4,913 43,971 65 48,949 29,867 19,082 62,630 1956 & 1997 7/73 40 Severna Park Marketplace, Severna Park, MD 63,254 512 12,700 51,066 — 63,766 9,233 54,533 30,888 9/11 40 Shops at Fairfax, Fairfax, VA 2,708 9,969 992 11,685 — 12,677 8,343 4,334 10,824 1975 & 1999 6/75 50 Smallwood Village Center, Waldorf, MD 17,819 8,218 6,402 19,629 6 26,037 8,087 17,950 — 1/06 40 Southdale, Glen Burnie, MD 18,895 24,825 15,254 28,465 1 43,720 21,947 21,773 — 1962 & 1986 1/72 40 Southside Plaza, Richmond, VA 6,728 10,998 1,878 15,848 — 17,726 12,466 5,260 — 1958 1/72 40 South Dekalb Plaza, Atlanta, GA 2,474 4,417 703 6,188 — 6,891 4,942 1,949 — 1970 2/76 40 Thruway, Winston-Salem, NC 7,848 25,568 7,693 25,679 44 33,416 17,777 15,639 36,711 1955 & 1965 5/72 40 Village Center, Centreville, VA 16,502 2,501 7,851 11,152 — 19,003 6,995 12,008 13,014 1990 8/93 40 Westview Village, Frederick, MD 6,047 25,265 6,047 25,262 3 31,312 8,590 22,722 — 2009 11/07, 02/15 50 White Oak, Silver Spring, MD 6,277 5,387 4,649 6,837 178 11,664 6,169 5,495 23,198 1958 & 1967 1/72 40 Other Buildings / Improvements 179 179 — 179 99 80 — Total Shopping Centers 832,397 413,662 412,358 822,249 11,452 1,246,059 357,235 888,824 629,111 Mixed-Use Properties Avenel Business Park, Gaithersburg, MD 21,459 31,401 3,756 49,104 — 52,860 37,712 15,148 27,222 1981-2000 12/84 35 & 40 Clarendon Center, Arlington, VA (1) 12,753 186,038 16,287 182,504 — 198,791 41,919 156,872 102,310 2010 7/73, 1/96 & 4/02 50 Park Van Ness, Washington, DC 2,242 91,690 2,242 91,690 — 93,932 7,778 86,154 69,691 2016 7/73 & 2/11 50 601 Pennsylvania Ave., Washington, DC 5,479 68,712 5,667 68,524 — 74,191 54,652 19,539 — 1986 7/73 35 Washington Square, Alexandria, VA 2,034 56,734 544 58,224 — 58,768 26,127 32,641 58,523 2000 7/73 50 7316 Wisconsin Avenue 39,641 934 38,662 980 933 40,575 95 40,480 — 1969 9/18 & 12/18 2 Total Mixed-Use Properties 83,608 435,509 67,158 451,026 933 519,117 168,283 350,834 257,746 Development Land Ashbrook Marketplace, Ashburn, VA 8,938 2,186 — — 11,124 11,124 — 11,124 — 5/18 Ashland Square Phase II, Manassas, VA 5,292 2,023 7,028 — 287 7,315 — 7,315 — 12/04 New Market, New Market, MD 2,088 286 2,374 — — 2,374 — 2,374 — 9/05 North Glebe Road, Arlington, VA 52,067 110,109 — — 162,176 162,176 — 162,176 23,332 — 8/14-8/16 Total Development Land 68,385 114,604 9,402 — 173,587 182,989 — 182,989 23,332 Total $ 984,390 $ 963,775 $ 488,918 $ 1,273,275 $ 185,972 $ 1,948,165 $ 525,518 $ 1,422,647 $ 910,189 (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 $1.35 billion at December 31, 2018 . 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, 2018 are summarized as follows: (In thousands) 2018 2017 2016 Total real estate investments: Balance, beginning of year $ 1,803,200 $ 1,700,813 $ 1,622,710 Acquisitions 48,579 77,258 48,123 Improvements 98,917 42,640 35,826 Retirements (2,531 ) (17,511 ) (5,846 ) Balance, end of year $ 1,948,165 $ 1,803,200 $ 1,700,813 Total accumulated depreciation: Balance, beginning of year $ 488,166 $ 458,279 $ 425,370 Depreciation expense 39,768 40,197 38,755 Retirements (2,416 ) (10,310 ) (5,846 ) Balance, end of year $ 525,518 $ 488,166 $ 458,279

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Nature of Operations	Nature of Operations 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.
Principles of Consolidation	Principles of Consolidation The accompanying consolidated financial statements include the accounts of Saul Centers, its subsidiaries, and the Operating Partnership and Subsidiary Partnerships which are majority owned by Saul Centers. 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 74.3% 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.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States 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. Actual results could differ from those estimates.
Real Estate Investment Properties	Real Estate Investment Properties The Company purchases real estate investment properties from time to time and records assets acquired and liabilities assumed, including land, buildings, and intangibles related to in-place leases and customer relationships, based on their relative fair values. The fair value of buildings generally is determined as if the buildings were vacant upon acquisition and then subsequently leased at market rental rates and considers the present value of all cash flows expected to be generated by the property including an initial lease up period. From time to time the Company may purchase a property for future development purposes. The property may be improved with an existing structure that would be demolished as part of the development. In such cases, the fair value of the building may be determined based only on existing leases and not include estimated cash flows related to future leases. In certain circumstances, such as if the building is vacant and the Company intends to demolish the building in the near term, the entire purchase price will be allocated to land. The Company determines the fair value of above and below market intangibles associated with in-place leases by assessing the net effective rent and remaining term of the lease relative to market terms for similar leases at acquisition taking into consideration the remaining contractual lease period, renewal periods, and the likelihood of the tenant exercising its renewal options. The fair value of a below market lease component is recorded as deferred income and accreted as additional lease revenue over the remaining contractual lease period. If the fair value of the below market lease intangible includes fair value associated with a renewal option, such amounts are not accreted until the renewal option is exercised. If the renewal option is not exercised the value is recognized at that time. The fair value of above market lease intangibles is recorded as a deferred asset and is amortized as a reduction of lease revenue over the remaining contractual lease term. The Company determines the fair value of at-market in-place leases considering the cost of acquiring similar leases, the foregone rents associated with the lease-up period and carrying costs associated with the lease-up period. Intangible assets associated with at-market in-place leases are amortized as additional expense over the remaining contractual lease term. To the extent customer relationship intangibles are present in an acquisition, the fair values of the intangibles are amortized over the lives of the customer relationships. The Company has never recorded a customer relationship intangible asset. Acquisition-related transaction costs are either (a) expensed as incurred when related to business combinations or (b) capitalized to land and/or building when related to asset acquisitions. 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 2018 , 2017 , or 2016 . Interest, real estate taxes, development related salary costs and other carrying costs are capitalized on projects under development and construction. Once construction is substantially completed and the assets are placed in service, their rental income, real estate tax expense, property operating expenses (consisting of payroll, repairs and maintenance, utilities, insurance and other property related expenses) and depreciation are included in current operations. Property operating expenses are charged to operations as incurred. Interest expense capitalized totaled $6.2 million , $3.5 million , and $ 2.5 million during 2018 , 2017 , and 2016 , respectively. Commercial development projects are considered substantially complete and available for occupancy upon completion of tenant improvements, but no later than one year from the cessation of major construction activity. Multi-family residential development projects are considered substantially complete and available for occupancy upon receipt of the certificate of occupancy from the appropriate licensing authority. Substantially completed portions of a project are accounted for as separate projects. 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.
Deferred Leasing Costs	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.
Construction in Progress	Construction in Progress Construction in progress includes 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.
Accounts Receivable and Accrued Income	Accounts Receivable and Accrued Income Accounts receivable primarily represent amounts currently due from tenants in accordance with the terms of the respective leases. 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.
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. 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.
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, 2018 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 Debt Costs	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 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.
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.
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, 2018 , 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.
Stock Based Employee Compensation, Deferred Compensation and Stock Plan for Directors	Stock Based Employee Compensation, Deferred Compensation and Stock Plan for Directors 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 in general and administrative expenses. The Company has a stock plan, which was originally approved in 2004, amended in 2008 and 2013 and which expires in 2023, for the purpose of attracting and retaining executive officers, directors and other key personnel (the "Stock Plan"). Pursuant to the Stock Plan, the Compensation Committee established a Deferred Compensation Plan for Directors for the benefit of its directors and their beneficiaries, which replaced a previous Deferred Compensation and Stock Plan for Directors. A director may make an annual election to defer all or part of his or her director’s fees and has the option to have the 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 the director elects to have fees paid in stock, fees earned during a calendar quarter are aggregated and divided by the common stock’s closing market price on the first trading day of the following quarter to determine the number of shares to be allocated to the director. As of December 31, 2018 , the directors’ deferred fee accounts comprise 114,644 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 Shareholders, and their issuance may not be deferred.
Noncontrolling Interest	Noncontrolling Interest Saul Centers is the sole general partner of the Operating Partnership, owning a 74.3% common interest as of December 31, 2018 . 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.
Per Share Data	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.
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 May 2014, the FASB issued ASU No. 2014-09 titled “Revenue from Contracts with Customers” and subsequently issued several related ASUs (collectively “ASU 2014-09”). ASU 2014-09 replaces most existing revenue recognition guidance and requires an entity to recognize the amount of revenue which it expects to be entitled for the transfer of promised goods or services to customers. ASU 2014-09 is effective for annual periods beginning after December 15, 2017, and interim periods within those years and early adoption is not permitted. ASU 2014-09 must be applied retrospectively by either restating prior periods or by recognizing the cumulative effect as of the first date of application. The Company adopted ASU 2014-09 effective January 1, 2018, using the modified retrospective approach. The adoption of ASU 2014-09 did not have an impact on the consolidated financial statements because the majority of the Company’s revenue consists of lease-related income from leasing arrangements, which is specifically excluded from ASU 2014-09. Other revenues, as a whole, are immaterial to total revenues. There was no change to previously reported amounts as a result of the adoption of ASU 2014-09. In February 2016, the FASB issued 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 anticipate election of the practical expedient with respect to cost recoveries. We anticipate that the accounting for initial direct costs will impact the amount of those costs that are charged to expense. In 2018, we capitalized approximately $2.1 million of initial direct costs that would have been charged to expense under ASU 2016-02. For those leases where we are lessee, the adoption of ASU 2016-02 will require us to record a right of use asset and a lease liability on the consolidated balance sheet. The right of use asset and lease liability are not expected to be material to the financial statements. 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. We are evaluating the impact that ASU 2016-13 will have on our consolidated financial statements and related disclosures. In January 2017, the FASB issued ASU 2017-01, "Clarifying the Definition of a Business" ("ASU 2017-01"). ASU 2017-01 provides that when substantially all of the fair value of the gross assets acquired is concentrated in a single identifiable asset or group of similar identifiable assets, the set is not a business. ASU 2017-01 is effective prospectively for annual periods beginning after December 15, 2017, and interim periods within those years. Early application is permitted for transactions for which the acquisition date occurs before the effective date provided the transaction has not been reported in the financial statements. The Company adopted ASU 2017-01 during the first quarter of 2017, the effect of which, for asset acquisitions, was (a) the capitalization of acquisition costs, instead of expense, and (b) recordation of acquired assets and assumed liabilities at relative fair value, instead of fair value.
Reclassifications	Reclassifications Certain reclassifications have been made to prior years to conform to the presentation used for year ended December 31, 2018 .

Organization, Formation, and _2

Organization, Formation, and Basis of Presentation (Tables)	12 Months Ended
	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Significant Properties Acquired, Developed and/or Disposed	The following table lists the significant properties acquired, developed and/or disposed of by the Company since January 1, 2016 . Name of Property Location Type Year of Acquisition/ Development/ Disposal Acquisitions Burtonsville Town Square Burtonsville, Maryland Shopping Center 2017 7316 Wisconsin Avenue Bethesda, Maryland Mixed-Use 2018 Developments 750 N. Glebe Road Arlington, Virginia Mixed-Use 2017-2018 Ashbrook Marketplace Ashburn, Virginia Shopping Center 2018 Dispositions Crosstown Business Center Tulsa, Oklahoma Mixed-Use 2016 Great Eastern District Heights, Maryland Shopping Center 2017

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Schedule of construction in progress	The following table shows the components of construction in progress. December 31, (in thousands) 2018 2017 N. Glebe Road $ 162,176 $ 83,462 Ashbrook Marketplace 11,124 — Other 12,672 7,652 Total $ 185,972 $ 91,114
Allowance for doubtful accounts	(In thousands) Year ended December 31, 2018 2017 2016 Beginning Balance $ 405 $ 1,958 $ 1,263 Provision for Credit Losses 685 906 1,494 Charge-offs (531 ) (2,459 ) (799 ) Ending Balance $ 559 $ 405 $ 1,958
Basic and diluted shares outstanding	December 31, (Shares in thousands) 2018 2017 2016 Weighted average common shares outstanding - Basic 22,383 21,901 21,505 Effect of dilutive options 42 107 110 Weighted average common shares outstanding - Diluted 22,425 22,008 21,615 Average share price $ 52.50 $ 61.63 $ 58.96 Non-dilutive options 492 — 129 Years non-dilutive options were issued 2015, 2016 and 2017 2007, 2015, and 2016

Real Estate Acquired (Tables)

Real Estate Acquired (Tables)	12 Months Ended
	Dec. 31, 2018
Real Estate [Abstract]
Allocation of purchase prices to acquired assets and liabilities	The purchase price was allocated to the assets acquired and liabilities assumed based on their fair value as shown in the following table. (in thousands) 700 N. Glebe Road Thruway Pad Total Land $ 7,236 $ 2,196 $ 9,432 Buildings — 874 874 In-place Leases — 93 93 Above Market Rent — — — Below Market Rent — (63 ) (63 ) Total Purchase Price $ 7,236 $ 3,100 $ 10,336 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, 2018 , 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 2019 $ 1,141 $ 102 $ 1,533 2020 785 52 1,434 2021 538 36 1,409 2022 383 33 1,306 2023 316 33 1,297 Thereafter 1,197 376 4,731 Total $ 4,360 $ 632 $ 11,710

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, 2018
Debt Disclosure [Abstract]
Summary of notes payable	The following is a summary of notes payable as of December 31, 2018 and 2017 . Notes Payable December 31, Interest Scheduled (Dollars in thousands) 2018 2017 Rate * Maturity * Fixed rate mortgages: $ — (a) $ 30,201 5.88 % Jan-2019 9,159 (b) 9,783 5.76 % May-2019 12,676 (c) 13,529 5.62 % Jul-2019 12,714 (d) 13,543 5.79 % Sep-2019 11,295 (e) 12,029 5.22 % Jan-2020 9,601 (f) 9,948 5.60 % May-2020 7,766 (g) 8,244 5.30 % Jun-2020 36,711 (h) 37,998 5.83 % Jul-2020 6,943 (i) 7,325 5.81 % Feb-2021 5,480 (j) 5,649 6.01 % Aug-2021 31,723 (k) 32,673 5.62 % Jun-2022 9,728 (l) 9,999 6.08 % Sep-2022 10,609 (m) 10,877 6.43 % Apr-2023 11,702 (n) 12,577 6.28 % Feb-2024 14,952 (o) 15,452 7.35 % Jun-2024 13,013 (p) 13,438 7.60 % Jun-2024 23,198 (q) 23,873 7.02 % Jul-2024 27,222 (r) 28,115 7.45 % Jul-2024 27,168 (s) 28,025 7.30 % Jan-2025 14,086 (t) 14,537 6.18 % Jan-2026 102,310 (u) 105,817 5.31 % Apr-2026 30,888 (v) 32,016 4.30 % Oct-2026 35,258 (w) 36,507 4.53 % Nov-2026 16,515 (x) 17,086 4.70 % Dec-2026 62,630 (y) 64,472 5.84 % May-2027 15,345 (z) 15,859 4.04 % Apr-2028 38,120 (aa) 39,968 3.51 % Jun-2028 15,547 (bb) 16,055 3.99 % Sep-2028 27,060 (cc) 27,884 3.69 % Mar-2030 14,526 (dd) 14,950 3.99 % Apr-2030 38,076 (ee) 39,140 3.39 % Feb-2032 69,691 (ff) 71,211 4.88 % Sep-2032 58,523 (gg) 60,000 3.75 % Dec-2032 31,941 (hh) — 4.41 % Nov-2033 22,900 (ii) — 4.69 % Jan-2034 11,781 (jj) 11,613 8.00 % Apr-2034 23,332 (kk) — 4.67 % Sep-2035 Total fixed rate 910,189 890,393 5.18 % 8.5 Years Variable rate loans: 47,000 (ll) 61,000 LIBOR + 1.35 % Jan-2022 75,000 (mm) — LIBOR + 1.30 % Jan-2023 — (nn) 14,135 LIBOR + 1.65 % Feb-2018 Total variable rate 122,000 75,135 3.84 % 3.7 Years Total notes payable $ 1,032,189 $ 965,528 5.02 % 8.0 Years * Interest rate and scheduled maturity data presented as of December 31, 2018 . Totals computed using weighted averages. Amounts shown are principal amounts and have not been reduced by any deferred debt issuance costs. (a) The loan was collateralized by three shopping centers, Broadlands Village, The Glen and Kentlands Square I, and required equal monthly principal and interest payments of $306,000 based upon a 25 -year amortization schedule and a final payment of $28.4 million at loan maturity. The loan was repaid in full in 2018 and replaced with two new loans. See (hh) and (ii) below. (b) The loan is collateralized by Olde Forte Village and requires equal monthly principal and interest payments of $98,000 based upon a 25 -year amortization schedule and a final payment of $9.0 million at loan maturity. Principal of $624,100 was amortized during 2018 . (c) The loan is collateralized by Countryside and requires equal monthly principal and interest payments of $133,000 based upon a 25 -year amortization schedule and a final payment of $12.3 million at loan maturity. Principal of $853,100 was amortized during 2018 . (d) The loan is collateralized by Briggs Chaney MarketPlace and requires equal monthly principal and interest payments of $133,000 based upon a 25 -year amortization schedule and a final payment of $12.2 million at loan maturity. Principal of $829,100 was amortized during 2018 . (e) The loan is collateralized by Shops at Monocacy and requires equal monthly principal and interest payments of $112,000 based upon a 25 -year amortization schedule and a final payment of $10.6 million at loan maturity. Principal of $733,800 was amortized during 2018 . (f) The loan is collateralized by Boca Valley Plaza and requires equal monthly principal and interest payments of $75,000 based upon a 30 -year amortization schedule and a final payment of $9.1 million at loan maturity. Principal of $347,300 was amortized during 2018 . (g) The loan is collateralized by Palm Springs Center and requires equal monthly principal and interest payments of $75,000 based upon a 25 -year amortization schedule and a final payment of $7.1 million at loan maturity. Principal of $477,900 was amortized during 2018 . (h) The loan and a corresponding interest-rate swap closed on June 29, 2010 and are collateralized by Thruway. On a combined basis, the loan and the interest-rate swap require equal monthly principal and interest payments of $289,000 based upon a 25 -year amortization schedule and a final payment of $34.8 million at loan maturity. Principal of $1.3 million was amortized during 2018 . (i) The loan is collateralized by Jamestown Place and requires equal monthly principal and interest payments of $66,000 based upon a 25 -year amortization schedule and a final payment of $6.1 million at loan maturity. Principal of $381,700 was amortized during 2018 . (j) The loan is collateralized by Hunt Club Corners and requires equal monthly principal and interest payments of $42,000 based upon a 30 -year amortization schedule and a final payment of $5.0 million , at loan maturity. Principal of $169,300 was amortized during 2018 . (k) The loan is collateralized by Lansdowne Town Center and requires monthly principal and interest payments of $230,000 based on a 30 -year amortization schedule and a final payment of $28.2 million at loan maturity. Principal of $949,600 was amortized during 2018 . (l) The loan is collateralized by Orchard Park and requires equal monthly principal and interest payments of $73,000 based upon a 30 -year amortization schedule and a final payment of $8.6 million at loan maturity. Principal of $270,300 was amortized during 2018 . (m) The loan is collateralized by BJ’s Wholesale and requires equal monthly principal and interest payments of $80,000 based upon a 30 -year amortization schedule and a final payment of $9.3 million at loan maturity. Principal of $268,400 was amortized during 2018 . (n) The loan is collateralized by Great Falls shopping center. The loan consists of three notes which require equal monthly principal and interest payments of $138,000 based upon a weighted average 26 -year amortization schedule and a final payment of $6.3 million at maturity. Principal of $874,800 was amortized during 2018 . (o) The loan is collateralized by Leesburg Pike and requires equal monthly principal and interest payments of $135,000 based upon a 25 -year amortization schedule and a final payment of $11.5 million at loan maturity. Principal of $499,800 was amortized during 2018 . (p) The loan is collateralized by Village Center and requires equal monthly principal and interest payments of $119,000 based upon a 25 -year amortization schedule and a final payment of $10.1 million at loan maturity. Principal of $424,700 was amortized during 2018 . (q) The loan is collateralized by White Oak and requires equal monthly principal and interest payments of $193,000 based upon a 24.4 year weighted amortization schedule and a final payment of $18.5 million at loan maturity. The loan was previously collateralized by Van Ness Square. During 2012, the Company substituted White Oak as the collateral and borrowed an additional $10.5 million . Principal of $675,200 was amortized during 2018 . (r) The loan is collateralized by Avenel Business Park and requires equal monthly principal and interest payments of $246,000 based upon a 25 -year amortization schedule and a final payment of $20.9 million at loan maturity. Principal of $893,200 was amortized during 2018 . (s) The loan is collateralized by Ashburn Village and requires equal monthly principal and interest payments of $240,000 based upon a 25 -year amortization schedule and a final payment of $20.5 million at loan maturity. Principal of $857,000 was amortized during 2018 . (t) The loan is collateralized by Ravenwood and requires equal monthly principal and interest payments of $111,000 based upon a 25 -year amortization schedule and a final payment of $10.1 million at loan maturity. Principal of $451,200 was amortized during 2018 . (u) The loan is collateralized by Clarendon Center and requires equal monthly principal and interest payments of $753,000 based upon a 25 -year amortization schedule and a final payment of $70.5 million at loan maturity. Principal of $3.5 million was amortized during 2018 . (v) The loan is collateralized by Severna Park MarketPlace and requires equal monthly principal and interest payments of $207,000 based upon a 25 -year amortization schedule and a final payment of $20.3 million at loan maturity. Principal of $1.1 million was amortized during 2018 . (w) The loan is collateralized by Kentlands Square II and requires equal monthly principal and interest payments of $240,000 based upon a 25 -year amortization schedule and a final payment of $23.1 million at loan maturity. Principal of $1.2 million was amortized during 2018 . (x) The loan is collateralized by Cranberry Square and requires equal monthly principal and interest payments of $113,000 based upon a 25 -year amortization schedule and a final payment of $10.9 million at loan maturity. Principal of $570,500 was amortized during 2018 . (y) The loan in the original amount of $73.0 million closed in May 2012, is collateralized by Seven Corners and requires equal monthly principal and interest payments of $463,200 based upon a 25 -year amortization schedule and a final payment of $42.3 million at loan maturity. Principal of $1.8 million was amortized during 2018 . (z) The loan is collateralized by Hampshire Langley and requires equal monthly principal and interest payments of $95,400 based upon a 25 -year amortization schedule and a final payment of $9.5 million at loan maturity. Principal of $513,700 was amortized in 2018 . (aa) The loan is collateralized by Beacon Center and requires equal monthly principal and interest payments of $268,500 based upon a 20 -year amortization schedule and a final payment of $17.1 million at loan maturity. Principal of $1.8 million was amortized in 2018 . (bb) The loan is collateralized by Seabreeze Plaza and requires equal monthly principal and interest payments of $94,900 based upon a 25 -year amortization schedule and a final payment of $9.5 million at loan maturity. Principal of $507,600 was amortized in 2018 . (cc) The loan is collateralized by Shops at Fairfax and Boulevard shopping centers and requires equal monthly principal and interest payments totaling $153,300 based upon a 25 -year amortization schedule and a final payment of $15.5 million at maturity. Principal of $824,000 was amortized in 2018 . (dd) The loan is collateralized by Northrock and requires equal monthly principal and interest payments totaling $84,400 based upon a 25 -year amortization schedule and a final payment of $8.4 million at maturity. Principal of $423,600 was amortized in 2018 . (ee) The loan is collateralized by Burtonsville Town Square and requires equal monthly principal and interest payments of $197,900 based on a 25 -year amortization schedule and a final payment of $20.3 million at loan maturity. Principal of $1.1 million was amortized in 2018 . (ff) The loan is a $71.6 million construction-to-permanent facility that is collateralized by and financed a portion of the construction costs of Park Van Ness. During the construction period, interest was funded by the loan. Effective September 1, 2017, the loan converted to permanent financing and requires monthly principal and interest payments totaling $413,500 based upon a 25 -year amortization schedule. A final payment of $39.6 million will be due at maturity. Principal of $1.5 million was amortized in 2018 . (gg) The loan is collateralized by Washington Square and requires equal monthly principal and interest payments of $308,500 based upon a 25 -year amortization schedule and a final payment of $31.1 million at loan maturity. Principal of $1.5 million was amortized in 2018 . (hh) The loan is collateralized by Broadlands Village and requires equal monthly principal and interest payments of $176,200 based on a 25 -year amortization schedule and a final payment of $17.3 million at loan maturity. Principal of $58,600 was amortized in 2018 . (ii) The loan is collateralized by The Glen and requires equal monthly principal and interest payments of $129,800 based on a 25 -year amortization schedule and a final payment of $12.5 million at loan maturity. (jj) The Company entered into a sale-leaseback transaction with its Olney property and is accounting for that transaction as a secured financing. The arrangement requires monthly payments of $60,400 which increase by 1.5% on May 1, 2015, and every May 1 thereafter. The arrangement provides for a final payment of $14.7 million and has an implicit interest rate of 8.0% . Negative amortization in 2018 totaled $168,600 . (kk) The loan is a $157.0 million construction-to-permanent facility that is collateralized by and will finance a portion of the construction costs of Glebe Road. During the construction period, interest will be funded by the loan. After conversion to a permanent loan, monthly principal and interest payments totaling $887,900 will be required based upon a 25 -year amortization schedule. (ll) The loan is a $325.0 million unsecured revolving credit facility. Interest accrues at a rate equal to the sum of one-month LIBOR plus a spread of 135 basis points. The line may be extended at the Company’s option for one year with payment of a fee of 0.15% . Monthly payments, if required, are interest only and vary depending upon the amount outstanding and the applicable interest rate for any given month. (mm) The loan is a $75.0 million unsecured term facility. Interest accrues at a rate equal to the sum of one-month LIBOR plus a spread of 130 basis points. Monthly payments are interest only. (nn) The loan was collateralized by Metro Pike Center and requires monthly principal and interest payments of approximately $48,000 and a final payment of $14.2 million at loan maturity. The loan was repaid in full during 2018 .
Scheduled maturities of all debt, including scheduled principal amortization	As of December 31, 2018 , 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 2019 $ 60,794 $ 2,257 $ 63,051 2020 61,163 28,042 89,205 2021 11,012 27,815 38,827 2022 83,502 (a) 28,381 111,883 2023 84,225 28,745 112,970 Thereafter 480,132 136,121 616,253 Principal amount $ 780,828 $ 251,361 1,032,189 Unamortized deferred debt costs 10,343 Net $ 1,021,846 (a) Includes $47.0 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, 2018 2017 2016 Interest incurred $ 49,652 $ 49,322 $ 46,867 Amortization of deferred debt costs 1,610 1,392 1,343 Capitalized interest (6,222 ) (3,489 ) (2,527 ) Total $ 45,040 $ 47,225 $ 45,683

Lease Agreements (Tables)

Lease Agreements (Tables)	12 Months Ended
	Dec. 31, 2018
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) 2019 $ 163,489 2020 146,425 2021 125,372 2022 101,778 2023 79,903 Thereafter 244,801 $ 861,768

Stock Option Plan (Tables)

Stock Option Plan (Tables)	12 Months Ended
	Dec. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock Options Issued	The following table summarizes the amount and activity of each grant, the total value and variables used in the computation and the amount expensed and included in general and administrative expense in the Consolidated Statements of Operations for the years ended December 31, 2018 , 2017 and 2016 . SAUL CENTERS, INC. (Dollars in thousands, except per share data) Stock options issued Directors Grant date 4/24/2009 5/7/2010 5/13/2011 5/4/2012 5/10/2013 5/9/2014 5/8/2015 5/6/2016 5/5/2017 5/11/2018 Subtotals Total grant 32,500 32,500 32,500 35,000 35,000 30,000 35,000 32,500 27,500 27,500 320,000 Vested 32,500 32,500 32,500 35,000 35,000 30,000 35,000 32,500 27,500 27,500 320,000 Exercised 30,000 27,500 25,000 25,000 22,500 17,500 12,500 7,500 — 2,500 170,000 Forfeited — 2,500 2,500 — — — — — 2,500 — 7,500 Exercisable at December 31, 2018 2,500 2,500 5,000 10,000 12,500 12,500 22,500 25,000 25,000 25,000 142,500 Remaining unexercised 2,500 2,500 5,000 10,000 12,500 12,500 22,500 25,000 25,000 25,000 142,500 Exercise price $ 32.68 $ 38.76 $ 41.82 $ 39.29 $ 44.42 $ 47.03 $ 51.07 $ 57.74 $ 59.41 $ 49.46 Volatility 0.344 0.369 0.358 0.348 0.333 0.173 0.166 0.166 0.173 0.192 Expected life (years) 6.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 Assumed yield 4.54 % 4.23 % 4.16 % 4.61 % 4.53 % 4.48 % 4.54 % 3.75 % 3.45 % 3.70 % Risk-free rate 2.19 % 2.17 % 1.86 % 0.78 % 0.82 % 1.63 % 1.50 % 1.23 % 1.89 % 2.84 % Total value at grant date $ 223 $ 288 $ 298 $ 257 $ 278 $ 110 $ 125 $ 151 $ 166 $ 169 $ 2,065 Expensed in previous years 223 288 298 257 278 110 125 — — — 1,579 Expensed in 2016 — — — — — — — 151 — — 151 Expensed in 2017 — — — — — — — — 166 — 166 Expensed in 2018 — — — — — — — — — 169 169 Future expense — — — — — — — — — — — Officers Grant date 5/13/2011 5/4/2012 5/10/2013 5/9/2014 5/8/2015 5/6/2016 5/5/2017 5/11/2018 Subtotals Grand Totals Total grant 162,500 242,500 202,500 170,000 190,000 194,000 205,000 217,500 1,584,000 1,904,000 Vested 118,750 107,500 171,875 168,125 140,625 96,375 51,250 — 854,500 1,174,500 Exercised 103,750 92,455 129,375 46,126 20,625 3,750 — — 396,081 566,081 Forfeited 43,750 135,000 30,625 1,875 3,125 1,875 — — 216,250 223,750 Exercisable at December 31, 2018 15,000 15,045 42,500 121,999 120,000 92,625 51,250 — 458,419 600,919 Remaining unexercised 15,000 15,045 42,500 121,999 166,250 188,375 205,000 217,500 971,669 1,114,169 Exercise price $ 41.82 $ 39.29 $ 44.42 $ 47.03 $ 51.07 $ 57.74 $ 59.41 $ 49.46 Volatility 0.330 0.315 0.304 0.306 0.298 0.185 0.170 0.177 Expected life (years) 8.0 8.0 8.0 7.0 7.0 7.0 7.0 7.0 Assumed yield 4.81 % 5.28 % 5.12 % 4.89 % 4.94 % 3.80 % 3.50 % 3.75 % Risk-free rate 2.75 % 1.49 % 1.49 % 2.17 % 1.89 % 1.55 % 2.17 % 2.94 % Gross value at grant date $ 1,367 $ 1,518 $ 1,401 $ 1,350 $ 1,585 $ 1,137 $ 1,324 $ 1,313 $ 10,995 $ 13,060 Estimated forfeitures 368 845 212 15 142 86 92 83 1,843 1,843 Expensed in previous years 999 576 762 492 240 — — — 3,069 4,648 Expensed in 2016 — 97 269 296 360 175 — — 1,197 1,348 Expensed in 2017 — — 158 295 361 263 205 — 1,282 1,448 Expensed in 2018 — — — 252 361 263 308 205 1,389 1,558 Future expense — — — — 121 350 719 1,025 2,215 2,215 Weighted average term of remaining future expense 2.5 years
Summary of Option Activity	The table below summarizes the option activity for the years 2018 , 2017 , and 2016 : 2018 2017 2016 Shares Weighted Shares Weighted Shares Weighted Outstanding at January 1 913,320 $ 52.80 833,630 $ 49.92 860,274 $ 46.58 Granted 245,000 49.46 232,500 59.41 226,500 57.74 Exercised (39,151 ) 42.98 (149,060 ) 46.97 (246,894 ) 45.59 Expired/Forfeited (5,000 ) 54.78 (3,750 ) 53.73 (6,250 ) 45.31 Outstanding December 31 1,114,169 52.40 913,320 52.80 833,630 49.92 Exercisable at December 31 600,919 50.93 430,945 48.94 375,255 46.68

Fair Value of Financial Instr_2

Fair Value of Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Changes in Fair Value of Swaps	The following chart summarizes the changes in fair value of the Company’s swap for the indicated periods. (Dollars in thousands) Year ended December 31, 2018 2017 2016 Increase (decrease) in fair value: Recognized in earnings $ (3 ) $ 70 $ (6 ) Recognized in other comprehensive income 594 812 678 Total $ 591 $ 882 $ 672

Distributions (Tables)

Distributions (Tables)	12 Months Ended
	Dec. 31, 2018
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, 2018 , 2017 , and 2016 , 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 2018 October 31 $ 2,953 $ 11,706 $ 4,062 216,476 $ 49.34 13,867 $ 50.20 July 31 2,953 11,590 4,055 201,500 51.68 13,107 52.60 April 30 2,672 11,545 3,942 85,202 47.54 42,422 47.83 January 31 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 October 31 $ 3,094 $ 11,221 $ 3,838 82,991 $ 59.33 15,596 $ 60.08 July 31 3,094 11,160 3,830 85,731 57.40 16,021 58.13 April 30 3,094 11,119 3,810 51,003 59.64 40,623 59.96 January 31 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 Distributions during 2016 October 31 $ 3,094 $ 10,168 $ 3,478 44,176 $ 57.18 30,891 $ 57.18 July 31 3,094 10,133 3,465 39,487 65.64 26,897 65.64 April 30 3,094 10,029 3,449 48,854 51.59 34,201 51.59 January 31 3,093 9,142 3,141 54,280 49.24 32,769 49.24 Total 2016 $ 12,375 $ 39,472 $ 13,533 186,797 124,758

Interim Results (Unaudited) (Ta

Interim Results (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2018
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 2018 and 2017 . (In thousands, except per share amounts) 2018 1st Quarter 2nd Quarter 3rd Quarter 4th Quarter Total revenue $ 56,496 $ 56,293 $ 57,059 $ 58,328 Operating income before loss on early extinguishment of debt, gain on casualty settlement, and noncontrolling interests 14,946 15,405 16,692 15,510 Gain on sales of properties — 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 (In thousands, except per share amounts) 2017 1st Quarter 2nd Quarter 3rd Quarter 4th Quarter Total revenue $ 58,466 $ 55,907 $ 56,237 $ 56,675 Operating income before loss on early extinguishment of debt, gain on casualty settlement, and noncontrolling interests 17,374 14,422 14,386 14,416 Gain on sales of properties — — — — Net income attributable to Saul Centers, Inc. 13,704 11,510 11,483 11,560 Net income available to common stockholders 10,610 8,416 8,390 8,466 Net income available to common stockholders per diluted share 0.49 0.38 0.38 0.38

Business Segments (Tables)

Business Segments (Tables)	12 Months Ended
	Dec. 31, 2018
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, 2018 Centers Properties and Other Totals Real estate rental operations: Revenue $ 164,671 $ 63,233 $ — $ 227,904 Expenses (34,970 ) (21,293 ) — (56,263 ) Income from real estate 129,701 41,940 — 171,641 Other revenue — — 272 272 Interest expense and amortization of deferred debt costs — — (45,040 ) (45,040 ) 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 $ 165,853 $ 61,352 $ — $ 227,205 Expenses (34,675 ) (20,917 ) — (55,592 ) Income from real estate 131,178 40,435 — 171,613 Other revenue — — 80 80 Interest expense and amortization of deferred debt costs — — (47,225 ) (47,225 ) 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 As of or for the year ended December 31, 2016 Real estate rental operations: Revenue $ 160,179 $ 56,840 $ — $ 217,019 Expenses (34,931 ) (18,770 ) — (53,701 ) Income from real estate 125,248 38,070 — 163,318 Other revenue — — 51 51 Interest expense and amortization of deferred debt costs — — (45,683 ) (45,683 ) General and administrative — — (17,496 ) (17,496 ) Depreciation and amortization of deferred leasing costs (29,964 ) (14,453 ) — (44,417 ) Acquisition related costs (60 ) — — (60 ) Change in fair value of derivatives — — (6 ) (6 ) Gain on sale of property — 1,013 — 1,013 Net income (loss) $ 95,224 $ 24,630 $ (63,134 ) $ 56,720 Capital investment $ 64,044 $ 27,001 $ — $ 91,045 Total assets $ 976,545 $ 358,419 $ 8,061 $ 1,343,025

Organization, Formation And Bas

Organization, Formation And Basis of Presentation - Additional Information (Detail)	Dec. 31, 2018partnershipproperty
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
Shopping Centers
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Number of real estate properties	49
Mixed-Use Properties
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Number of real estate properties	7
Non-operating Development Properties
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Number of real estate properties	4

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2018USD ($)tenantstoreshares	Dec. 31, 2017USD ($)shares	Dec. 31, 2016USD ($)shares	Dec. 31, 2015USD ($)
Significant Accounting Policies [Line Items]
Number of shopping centers | store	32
Capitalized interest	$ (6,222,000)	$ (3,489,000)	$ (2,527,000)
Depreciation and amortization of deferred leasing costs	39,768,000	40,197,000	38,755,000
Repairs and maintenance expense	11,900,000	11,600,000	11,800,000
Deferred leasing costs, net	28,083,000	27,255,000
Accumulated amortization deferred leasing cost	37,700,000	35,300,000
Amortization expense deferred leasing cost	6,100,000	5,500,000	5,600,000
Allowance for doubtful accounts receivables	559,000	405,000	1,958,000	$ 1,263,000
Accounts receivable, net representing rental income accrued	43,300,000	44,100,000
Allowance for doubtful accounts receivables representing rental income accrued	100,000	200,000
Deferred debt costs, net of accumulated amortization	10,343,000	6,900,000
Accumulated amortization	7,300,000	8,200,000
Accrued penalties and interest	0	0	$ 0
Tax basis of the company's real estate investments	$ 1,350,000,000	$ 1,320,000,000
Shares issued to directors (in shares) | shares	43,150	152,758	251,323
Shares issued to directors	$ 1,558,000	$ 1,448,000	$ 1,348,000
Capitalized lease costs	$ 2,100,000
Director
Significant Accounting Policies [Line Items]
Shares credited to deferred fee accounts (in shares) | shares	114,644
Shares issued to directors (in shares) | shares	200	200	200
Shares issued to directors	$ 108,800	$ 130,700	$ 150,100
Minimum | Building
Significant Accounting Policies [Line Items]
Estimated useful life	35 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
Revenue
Significant Accounting Policies [Line Items]
Number of tenants | tenant	2
Revenue | Minimum
Significant Accounting Policies [Line Items]
Percentage of total revenue	2.50%
Revenue | Giant Food
Significant Accounting Policies [Line Items]
Percentage of total revenue	4.70%
Number of shopping centers | store	10
Revenue | Capital One
Significant Accounting Policies [Line Items]
Percentage of total revenue	2.70%
Number of shopping centers | store	17
Glebe Road Construction Loan
Significant Accounting Policies [Line Items]
Deferred debt costs, net of accumulated amortization	$ 1,800,000
Saul Holdings Limited Partnership
Significant Accounting Policies [Line Items]
Percentage of ownership in operating partnership	74.30%

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Construction in Progress (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Construction in progress	$ 185,972	$ 91,114
N. Glebe Road
Property, Plant and Equipment [Line Items]
Construction in progress	162,176	83,462
Ashbrook Marketplace
Property, Plant and Equipment [Line Items]
Construction in progress	11,124	0
Other
Property, Plant and Equipment [Line Items]
Construction in progress	$ 12,672	$ 7,652

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Allowance for Doubtful Accounts (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Allowance for Doubtful Accounts Receivable [Roll Forward]
Beginning Balance	$ 405	$ 1,958	$ 1,263
Provision for Credit Losses	685	906	1,494
Charge-offs	(531)	(2,459)	(799)
Ending Balance	$ 559	$ 405	$ 1,958

Summary of Significant Accoun_7

Summary of Significant Accounting Policies - Basic and Diluted Shares Outstanding (Detail) - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Weighted average common shares outstanding - basic (in shares)	22,383	21,901	21,505
Effect of dilutive options (in shares)	42	107	110
Weighted average common shares outstanding - diluted (in shares)	22,425	22,008	21,615
Average share price (in usd per share)	$ 52.50	$ 61.63	$ 58.96
Options
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Non-dilutive options (in shares)	492	0	129

Real Estate Acquired - Addition

Real Estate Acquired - Additional Information (Detail) ft² in Thousands	May 09, 2018shares	Dec. 31, 2018USD ($)ft²apartment	Sep. 30, 2018USD ($)	May 31, 2018USD ($)ashares	Mar. 31, 2017USD ($)	Jan. 31, 2017USD ($)	Aug. 31, 2016USD ($)a	Sep. 30, 2015USD ($)	Dec. 31, 2014USD ($)	Aug. 31, 2014USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2018USD ($)ft²apartment	Dec. 31, 2017USD ($)property	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Real Estate Properties [Line Items]
Payments to acquire real estate												$ 12,883,000	$ 17,653,000	$ 15,564,000
Acquisition costs				$ 200,000										60,400
Rent expense												779,800	$ 774,700	843,300
Area of real estate property (in square feet) | a				13,700			13,700
Number of properties acquired | property													1
Purchase price allocated to land		$ 488,918,000										488,918,000
Purchase price allocated to buildings		1,273,275,000										1,273,275,000
Below market lease, carrying amount		24,800,000										24,800,000	$ 25,100,000
Below market lease, accumulated amortization		13,100,000										13,100,000	11,800,000
Accretion income, intangible liabilities												1,700,000	1,700,000	1,800,000
Total Purchase Price		1,948,165,000									$ 1,700,813,000	1,948,165,000	1,803,200,000	1,700,813,000	$ 1,622,710,000
Lease acquisition costs
Real Estate Properties [Line Items]
Intangible assets gross carrying amount		12,500,000										12,500,000	12,300,000
Intangible assets, accumulated amortization		8,100,000										8,100,000	7,500,000
Amortization expense												$ 1,300,000	1,100,000	1,000,000
Weighted-average amortization period												4 years 1 month 6 days
Above Market Rent
Real Estate Properties [Line Items]
Intangible assets gross carrying amount		800,000										$ 800,000	600,000
Intangible assets, accumulated amortization		100,000										100,000	39,500
Amortization expense												$ 110,500	31,600	1,500
Weighted-average amortization period												7 years 2 months 12 days
Below Market Rent
Real Estate Properties [Line Items]
Weighted-average amortization period												5 years 6 months
750 N. Glebe Road
Real Estate Properties [Line Items]
Payments to acquire real estate										$ 40,000,000
Acquisition costs										$ 400,000
730 N. Glebe Road
Real Estate Properties [Line Items]
Payments to acquire real estate									$ 2,800,000
Acquisition costs									$ 40,400
726 N Glebe Road
Real Estate Properties [Line Items]
Payments to acquire real estate								$ 4,000,000
Acquisition costs								$ 100,000
700 N. Glebe Road
Real Estate Properties [Line Items]
Payments to acquire real estate							$ 7,200,000
Purchase price allocated to land											7,236,000			7,236,000
Purchase price allocated to buildings											0			0
Total Purchase Price											7,236,000			7,236,000
700 N. Glebe Road | In-place Leases
Real Estate Properties [Line Items]
Intangible assets											0			0
700 N. Glebe Road | Above Market Rent
Real Estate Properties [Line Items]
Intangible assets											0			0
700 N. Glebe Road | Below Market Rent
Real Estate Properties [Line Items]
Intangible assets											0			0
Thruway Pad
Real Estate Properties [Line Items]
Payments to acquire real estate							3,100,000
Acquisition costs							$ 60,400
Purchase price allocated to land											2,196,000			2,196,000
Purchase price allocated to buildings											874,000			874,000
Total Purchase Price											3,100,000			3,100,000
Thruway Pad | In-place Leases
Real Estate Properties [Line Items]
Intangible assets											93,000			93,000
Thruway Pad | Above Market Rent
Real Estate Properties [Line Items]
Intangible assets											0			0
Thruway Pad | Below Market Rent
Real Estate Properties [Line Items]
Intangible assets											63,000			63,000
Beacon Center
Real Estate Properties [Line Items]
Payments to acquire real estate											22,700,000
Rent expense											60,000
Mortgage loans on real estate, period increase (decrease)											11,250,000
Southdale
Real Estate Properties [Line Items]
Payments to acquire real estate											15,300,000
Rent expense											60,000
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
2016 Acquisitions
Real Estate Properties [Line Items]
Payments to acquire real estate														10,300,000
Purchase price allocated to land											9,432,000			9,432,000
Purchase price allocated to buildings											874,000			874,000
Total Purchase Price											10,336,000			10,336,000
2016 Acquisitions | In-place Leases
Real Estate Properties [Line Items]
Intangible assets											93,000			93,000
2016 Acquisitions | Above Market Rent
Real Estate Properties [Line Items]
Intangible assets											0			0
2016 Acquisitions | Below Market Rent
Real Estate Properties [Line Items]
Intangible assets											$ 63,000			$ 63,000
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]
Purchase price allocated to land		47,438,000										$ 47,438,000
Purchase price allocated to buildings		979,000										979,000
Total Purchase Price		49,450,000										49,450,000
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				$ 8,776,000
7316 Wisconsin Avenue
Real Estate Properties [Line Items]
Payments to acquire real estate			$ 35,500,000
Acquisition costs			$ 700,000
Parcel Adjacent to 7316 Wisconsin Avenue
Real Estate Properties [Line Items]
Payments to acquire real estate		$ 4,500,000
7316 Wisconsin Avenue Retail Space
Real Estate Properties [Line Items]
Area of real estate property (in acres) | ft²		10										10
BF Saul Real Estate Investment Trust | Ashbrook Marketplace
Real Estate Properties [Line Items]
Limited partnership units issued (in shares) | shares	176,680			176,680
Maximum | 7316 Wisconsin Avenue
Real Estate Properties [Line Items]
Number of units in real estate property | apartment		325										325
Maximum | 7316 Wisconsin Avenue Additional Apartment Units
Real Estate Properties [Line Items]
Number of units in real estate property | apartment		40										40

Real Estate Acquired - Allocati

Real Estate Acquired - Allocation of Purchase Prices to Acquired Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Real Estate Properties [Line Items]
Land	$ 488,918
Buildings	1,273,275
Total Purchase Price	1,948,165	$ 1,803,200	$ 1,700,813	$ 1,622,710
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)
700 N. Glebe Road
Real Estate Properties [Line Items]
Land			7,236
Buildings			0
Total Purchase Price			7,236
700 N. Glebe Road | In-place Leases
Real Estate Properties [Line Items]
Intangible assets			0
700 N. Glebe Road | Above Market Rent
Real Estate Properties [Line Items]
Intangible assets			0
700 N. Glebe Road | Below Market Rent
Real Estate Properties [Line Items]
Intangible assets			0
Thruway Pad
Real Estate Properties [Line Items]
Land			2,196
Buildings			874
Total Purchase Price			3,100
Thruway Pad | In-place Leases
Real Estate Properties [Line Items]
Intangible assets			(93)
Thruway Pad | Above Market Rent
Real Estate Properties [Line Items]
Intangible assets			0
Thruway Pad | Below Market Rent
Real Estate Properties [Line Items]
Intangible assets			(63)
2016 Acquisitions
Real Estate Properties [Line Items]
Land			9,432
Buildings			874
Total Purchase Price			10,336
2016 Acquisitions | In-place Leases
Real Estate Properties [Line Items]
Intangible assets			(93)
2016 Acquisitions | Above Market Rent
Real Estate Properties [Line Items]
Intangible assets			0
2016 Acquisitions | Below Market Rent
Real Estate Properties [Line Items]
Intangible assets			$ (63)

Real Estate Acquired - Amortiza

Real Estate Acquired - Amortization of Intangible Assets and Deferred Income Related to in Place Leases (Detail) $ in Thousands	Dec. 31, 2018USD ($)
Below market leases
2,019	$ 1,533
2,020	1,434
2,021	1,409
2,022	1,306
2,023	1,297
Thereafter	4,731
Total	11,710
Lease acquisition costs
Finite-Lived Intangible Assets [Line Items]
2,019	1,141
2,020	785
2,021	538
2,022	383
2,023	316
Thereafter	1,197
Total	4,360
Above market leases
Finite-Lived Intangible Assets [Line Items]
2,019	102
2,020	52
2,021	36
2,022	33
2,023	33
Thereafter	376
Total	$ 632

Noncontrolling Interests - Ho_2

Noncontrolling Interests - Holders of Convertible Limited Partnership Units in Operating Partnership - Additional Information (Detail) - Noncontrolling Interests	12 Months Ended
	Dec. 31, 2018shares	Dec. 31, 2017shares	Dec. 31, 2016shares
Noncontrolling Interest [Line Items]
Limited partnership units (in shares)	7,825,980
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)	920,000
Fully converted partnership units and diluted weighted average shares outstanding (in shares)	30,156,100	29,510,900	28,989,900
Saul Holdings Limited Partnership
Noncontrolling Interest [Line Items]
Percentage of ownership interest of noncontrolling interest	25.70%

Mortgage Notes Payable, Revol_3

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

Dec. 18, 2018

Oct. 03, 2018

Nov. 20, 2017

Aug. 14, 2017

Jan. 18, 2017

Sep. 30, 2017

Dec. 31, 2021

Dec. 31, 2018

Oct. 01, 2021

Oct. 01, 2020

Oct. 01, 2019

Dec. 31, 2017

Sep. 01, 2017

Dec. 31, 2016

Nov. 30, 2016

Debt Instrument [Line Items]

Outstanding debt

$ 1,000,000,000

Fixed rate mortgages

880,271,000

$ 897,888,000

Variable rate debt

74,591,000

0

Principal amount

1,032,189,000

965,500,000

Debt outstanding with fixed-rate

890,400,000

Debt outstanding with variable-rate

75,100,000

Remaining loan balance

251,361,000

Capitalization of debt issuance cost

3,200,000

2,600,000

$ 100,000

Mortgage Notes Payable

Debt Instrument [Line Items]

Guarantor obligations, maximum exposure

51,000,000

51,000,000

Fixed rate mortgage notes payable

Debt Instrument [Line Items]

Fixed rate mortgages

910,189,000

890,393,000

Fixed rate mortgage notes payable | Washington Square

Debt Instrument [Line Items]

Remaining loan balance

$ 28,100,000

Fixed rate mortgage notes payable | 3.51% due June 2028

Debt Instrument [Line Items]

Fixed rate mortgages

38,120,000

39,968,000

Fixed rate mortgage notes payable | 3.51% due June 2028 | Beacon Center

Debt Instrument [Line Items]

Loan amount

$ 11,250,000

Loan required periodic principal and interest payment

268,500

Fixed rate mortgage notes payable | 3.39% due January 2032

Debt Instrument [Line Items]

Fixed rate mortgages

38,076,000

39,140,000

Fixed rate mortgage notes payable | 4.67% Construction To Permanent Loan Due 2035

Debt Instrument [Line Items]

Fixed rate mortgages

23,332,000

0

Fixed rate mortgage notes payable | 4.88% due September 2032

Debt Instrument [Line Items]

Fixed rate mortgages

69,691,000

71,211,000

Fixed rate mortgage notes payable | 3.75% due December 2032

Debt Instrument [Line Items]

Fixed rate mortgages

58,523,000

60,000,000

Fixed rate mortgage notes payable | 3.69% Due March 2030

Debt Instrument [Line Items]

Fixed rate mortgages

27,060,000

27,884,000

Fixed rate mortgage notes payable | 3.99% Due April 2030

Debt Instrument [Line Items]

Fixed rate mortgages

14,526,000

14,950,000

Fixed rate mortgage notes payable | 4.41% mortgage maturing 2033

Debt Instrument [Line Items]

Fixed rate mortgages

31,941,000

0

Fixed rate mortgage notes payable | 4.69% fixed rate loan maturing in 2034

Debt Instrument [Line Items]

Fixed rate mortgages

22,900,000

0

Variable rate loans payable

Debt Instrument [Line Items]

Variable rate debt

$ 122,000,000

75,135,000

Interest rate spread on LIBOR

3.84%

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

$ 190,700,000

Outstanding line of credit

47,000,000

Letter of credit available borrowing capacity

184,600

New Facility | Revolving Credit Facility | Line of Credit

Debt Instrument [Line Items]

Variable rate debt

47,000,000

61,000,000

Line of credit facility, maximum borrowing capacity

$ 325,000,000

Interest rate spread on LIBOR

1.35%

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

Debt Instrument [Line Items]

Interest rate spread on LIBOR

1.35%

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

Debt Instrument [Line Items]

Interest rate spread on LIBOR

1.95%

New Facility | Revolving Credit Facility | Term Facility

Debt Instrument [Line Items]

Interest rate spread on LIBOR

1.30%

New Facility | Revolving Credit Facility | Term Facility | Minimum

Debt Instrument [Line Items]

Interest rate spread on LIBOR

1.30%

New Facility | Revolving Credit Facility | Term Facility | Maximum

Debt Instrument [Line Items]

Interest rate spread on LIBOR

1.90%

New Facility | Term Facility | Line of Credit

Debt Instrument [Line Items]

Variable rate debt

$ 75,000,000

0

Line of credit facility, maximum borrowing capacity

$ 75,000,000

Interest rate spread on LIBOR

1.30%

Park Van Ness Loan

Debt Instrument [Line Items]

Fixed rate mortgages

$ 69,700,000

Guarantor obligations, maximum exposure

10,000,000

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 II Bank Loan | Fixed rate mortgage notes payable

Debt Instrument [Line Items]

Guarantor obligations, maximum exposure

8,800,000

Remaining loan balance

35,300,000

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

Glebe Road 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

4,000,000

Remaining loan balance

31,900,000

Broadlands Village | 4.41% mortgage maturing 2033

Debt Instrument [Line Items]

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

Debt Covenant

Debt Instrument [Line Items]

Carrying value of properties collateralized

$ 1,100,000,000

$ 1,000,000,000

Credit agreement leverage ratio

60.00%

Interest coverage ratio required minimum

2

Required fixed charge coverage ratio

1.4

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

Scenario, Forecast | Park Van Ness Loan

Debt Instrument [Line Items]

Guarantor obligations, maximum exposure

$ 0

$ 3,300,000

$ 6,700,000

Scenario, Forecast | Glebe Road 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

$ 71,580,000

Loan required periodic principal and interest payment

$ 413,500

Balloon payment to be paid

$ 39,600,000

Mortgage Notes Payable, Revol_4

Mortgage Notes Payable, Revolving Credit Facility, Interest Expense and Amortization of Deferred Debt Costs - Summary of Notes Payable (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Notes Payable [Line Items]
Fixed rate mortgages	$ 880,271	$ 897,888
Interest rate	4.40%	3.90%
Variable rate debt	$ 74,591	$ 0
Scheduled maturity period	7 years 11 months 14 days
Total notes payable	$ 1,032,189	965,528
Interest rate during period	5.02%
Fixed rate mortgage notes payable
Notes Payable [Line Items]
Fixed rate mortgages	$ 910,189	890,393
Interest rate	5.18%
Scheduled maturity period	8 years 6 months 10 days
Fixed rate mortgage notes payable | 5.88% due January 2019
Notes Payable [Line Items]
Fixed rate mortgages	$ 0	30,201
Interest rate	5.88%
Fixed rate mortgage notes payable | 5.76% due May 2019
Notes Payable [Line Items]
Fixed rate mortgages	$ 9,159	9,783
Interest rate	5.76%
Fixed rate mortgage notes payable | 5.62% due July 2019
Notes Payable [Line Items]
Fixed rate mortgages	$ 12,676	13,529
Interest rate	5.62%
Fixed rate mortgage notes payable | 5.79% due September 2019
Notes Payable [Line Items]
Fixed rate mortgages	$ 12,714	13,543
Interest rate	5.79%
Fixed rate mortgage notes payable | 5.22% due January 2020
Notes Payable [Line Items]
Fixed rate mortgages	$ 11,295	12,029
Interest rate	5.22%
Fixed rate mortgage notes payable | 5.60% due May 2020
Notes Payable [Line Items]
Fixed rate mortgages	$ 9,601	9,948
Interest rate	5.60%
Fixed rate mortgage notes payable | 5.30% due June 2020
Notes Payable [Line Items]
Fixed rate mortgages	$ 7,766	8,244
Interest rate	5.30%
Fixed rate mortgage notes payable | 5.83% due July 2020
Notes Payable [Line Items]
Fixed rate mortgages	$ 36,711	37,998
Interest rate	5.83%
Fixed rate mortgage notes payable | 5.81% due February 2021
Notes Payable [Line Items]
Fixed rate mortgages	$ 6,943	7,325
Interest rate	5.81%
Fixed rate mortgage notes payable | 6.01% due August 2021
Notes Payable [Line Items]
Fixed rate mortgages	$ 5,480	5,649
Interest rate	6.01%
Fixed rate mortgage notes payable | 5.62% due June 2022
Notes Payable [Line Items]
Fixed rate mortgages	$ 31,723	32,673
Interest rate	5.62%
Fixed rate mortgage notes payable | 6.08% due September 2022
Notes Payable [Line Items]
Fixed rate mortgages	$ 9,728	9,999
Interest rate	6.08%
Fixed rate mortgage notes payable | 6.43% due April 2023
Notes Payable [Line Items]
Fixed rate mortgages	$ 10,609	10,877
Interest rate	6.43%
Fixed rate mortgage notes payable | 6.28% due February 2024
Notes Payable [Line Items]
Fixed rate mortgages	$ 11,702	12,577
Interest rate	6.28%
Fixed rate mortgage notes payable | 7.35% due June 2024
Notes Payable [Line Items]
Fixed rate mortgages	$ 14,952	15,452
Interest rate	7.35%
Fixed rate mortgage notes payable | 7.60% due June 2024
Notes Payable [Line Items]
Fixed rate mortgages	$ 13,013	13,438
Interest rate	7.60%
Fixed rate mortgage notes payable | 7.02% due July 2024
Notes Payable [Line Items]
Fixed rate mortgages	$ 23,198	23,873
Interest rate	7.02%
Fixed rate mortgage notes payable | 7.45% due July 2024
Notes Payable [Line Items]
Fixed rate mortgages	$ 27,222	28,115
Interest rate	7.45%
Fixed rate mortgage notes payable | 7.30% due January 2025
Notes Payable [Line Items]
Fixed rate mortgages	$ 27,168	28,025
Interest rate	7.30%
Fixed rate mortgage notes payable | 6.18% due January 2026
Notes Payable [Line Items]
Fixed rate mortgages	$ 14,086	14,537
Interest rate	6.18%
Fixed rate mortgage notes payable | 5.31% due April 2026
Notes Payable [Line Items]
Fixed rate mortgages	$ 102,310	105,817
Interest rate	5.31%
Fixed rate mortgage notes payable | 4.30% due October 2026
Notes Payable [Line Items]
Fixed rate mortgages	$ 30,888	32,016
Interest rate	4.30%
Fixed rate mortgage notes payable | 4.53% due November 2026
Notes Payable [Line Items]
Fixed rate mortgages	$ 35,258	36,507
Interest rate	4.53%
Fixed rate mortgage notes payable | 4.70% due December 2026
Notes Payable [Line Items]
Fixed rate mortgages	$ 16,515	17,086
Interest rate	4.70%
Fixed rate mortgage notes payable | 5.84% due May 2027
Notes Payable [Line Items]
Fixed rate mortgages	$ 62,630	64,472
Interest rate	5.84%
Fixed rate mortgage notes payable | 4.04% due April 2028
Notes Payable [Line Items]
Fixed rate mortgages	$ 15,345	15,859
Interest rate	4.04%
Fixed rate mortgage notes payable | 3.51% due June 2028
Notes Payable [Line Items]
Fixed rate mortgages	$ 38,120	39,968
Interest rate	3.51%
Fixed rate mortgage notes payable | 3.99% due September 2028
Notes Payable [Line Items]
Fixed rate mortgages	$ 15,547	16,055
Interest rate	3.99%
Fixed rate mortgage notes payable | 3.69% Due March 2030
Notes Payable [Line Items]
Fixed rate mortgages	$ 27,060	27,884
Interest rate	3.69%
Fixed rate mortgage notes payable | 3.99% Due April 2030
Notes Payable [Line Items]
Fixed rate mortgages	$ 14,526	14,950
Interest rate	3.99%
Fixed rate mortgage notes payable | 3.39% due January 2032
Notes Payable [Line Items]
Fixed rate mortgages	$ 38,076	39,140
Interest rate	3.39%
Fixed rate mortgage notes payable | 4.88% due September 2032
Notes Payable [Line Items]
Fixed rate mortgages	$ 69,691	71,211
Interest rate	4.88%
Fixed rate mortgage notes payable | 3.75% due December 2032
Notes Payable [Line Items]
Fixed rate mortgages	$ 58,523	60,000
Interest rate	3.75%
Fixed rate mortgage notes payable | 4.41% mortgage maturing 2033
Notes Payable [Line Items]
Fixed rate mortgages	$ 31,941	0
Interest rate	4.41%
Fixed rate mortgage notes payable | 4.69% fixed rate loan maturing in 2034
Notes Payable [Line Items]
Fixed rate mortgages	$ 22,900	0
Interest rate	4.69%
Fixed rate mortgage notes payable | 8.00% due April 2034
Notes Payable [Line Items]
Fixed rate mortgages	$ 11,781	11,613
Interest rate	8.00%
Fixed rate mortgage notes payable | 4.67% Construction To Permanent Loan Due 2035
Notes Payable [Line Items]
Fixed rate mortgages	$ 23,332	0
Interest rate	4.67%
Variable rate loans payable
Notes Payable [Line Items]
Variable rate debt	$ 122,000	75,135
Interest rate spread on LIBOR	3.84%
Scheduled maturity period	3 years 8 months 8 days
Variable rate loans payable | Metro Pike Center Bank Loan
Notes Payable [Line Items]
Variable rate debt	$ 0	14,135
Interest rate spread on LIBOR	1.65%
Revolving Credit Facility | New Facility | Line of Credit
Notes Payable [Line Items]
Variable rate debt	$ 47,000	61,000
Interest rate spread on LIBOR	1.35%
Revolving Credit Facility | New Facility | Term Facility
Notes Payable [Line Items]
Interest rate spread on LIBOR	1.30%
Term Facility | New Facility | Line of Credit
Notes Payable [Line Items]
Variable rate debt	$ 75,000	$ 0
Interest rate spread on LIBOR	1.30%

Mortgage Notes Payable, Revol_5

Mortgage Notes Payable, Revolving Credit Facility, Interest Expense and Amortization of Deferred Debt Costs - Summary of Notes Payable (Additional Information) (Detail)	12 Months Ended
	Dec. 31, 2018USD ($)shopping_centernote	Dec. 31, 2017USD ($)	Sep. 01, 2017USD ($)	Dec. 31, 2012USD ($)
Notes Payable [Line Items]
Interest rate	4.40%	3.90%
Fixed rate mortgages	$ 880,271,000	$ 897,888,000
Fixed rate mortgage notes payable
Notes Payable [Line Items]
Interest rate	5.18%
Fixed rate mortgages	$ 910,189,000	890,393,000
Fixed rate mortgage notes payable | 5.88% due January 2019
Notes Payable [Line Items]
Interest rate	5.88%
Fixed rate mortgages	$ 0	30,201,000
Fixed rate mortgage notes payable | 5.88% due January 2019 | Broadlands Village, The Glen and Kentlands Square I
Notes Payable [Line Items]
Number of shopping centers | shopping_center	3
Principal and interest payments	$ 306,000
Balloon payment to be paid	$ 28,400,000
Amortization period	25 years
Number of notes | note	2
Fixed rate mortgage notes payable | 5.76% due May 2019
Notes Payable [Line Items]
Interest rate	5.76%
Fixed rate mortgages	$ 9,159,000	9,783,000
Fixed rate mortgage notes payable | 5.76% due May 2019 | Olde Forte Village
Notes Payable [Line Items]
Principal and interest payments	98,000
Balloon payment to be paid	$ 9,000,000
Amortization period	25 years
Amortization of principal	$ 624,100
Fixed rate mortgage notes payable | 5.62% due July 2019
Notes Payable [Line Items]
Interest rate	5.62%
Fixed rate mortgages	$ 12,676,000	13,529,000
Fixed rate mortgage notes payable | 5.62% due July 2019 | Countryside
Notes Payable [Line Items]
Principal and interest payments	133,000
Balloon payment to be paid	$ 12,300,000
Amortization period	25 years
Amortization of principal	$ 853,100
Fixed rate mortgage notes payable | 5.79% due September 2019
Notes Payable [Line Items]
Interest rate	5.79%
Fixed rate mortgages	$ 12,714,000	13,543,000
Fixed rate mortgage notes payable | 5.79% due September 2019 | Briggs Chancy MarketPlace
Notes Payable [Line Items]
Principal and interest payments	133,000
Balloon payment to be paid	$ 12,200,000
Amortization period	25 years
Amortization of principal	$ 829,100
Fixed rate mortgage notes payable | 5.22% due January 2020
Notes Payable [Line Items]
Interest rate	5.22%
Fixed rate mortgages	$ 11,295,000	12,029,000
Fixed rate mortgage notes payable | 5.22% due January 2020 | Shops at Monocacy
Notes Payable [Line Items]
Principal and interest payments	112,000
Balloon payment to be paid	$ 10,600,000
Amortization period	25 years
Amortization of principal	$ 733,800
Fixed rate mortgage notes payable | 5.60% due May 2020
Notes Payable [Line Items]
Interest rate	5.60%
Fixed rate mortgages	$ 9,601,000	9,948,000
Fixed rate mortgage notes payable | 5.60% due May 2020 | Boca Valley Plaza
Notes Payable [Line Items]
Principal and interest payments	75,000
Balloon payment to be paid	$ 9,100,000
Amortization period	30 years
Amortization of principal	$ 347,300
Fixed rate mortgage notes payable | 5.30% due June 2020
Notes Payable [Line Items]
Interest rate	5.30%
Fixed rate mortgages	$ 7,766,000	8,244,000
Fixed rate mortgage notes payable | 5.30% due June 2020 | Palm Springs Center
Notes Payable [Line Items]
Principal and interest payments	75,000
Balloon payment to be paid	$ 7,100,000
Amortization period	25 years
Amortization of principal	$ 477,900
Fixed rate mortgage notes payable | 5.83% due July 2020
Notes Payable [Line Items]
Interest rate	5.83%
Fixed rate mortgages	$ 36,711,000	37,998,000
Fixed rate mortgage notes payable | 5.83% due July 2020 | Thruway
Notes Payable [Line Items]
Principal and interest payments	289,000
Balloon payment to be paid	$ 34,800,000
Amortization period	25 years
Amortization of principal	$ 1,300,000
Fixed rate mortgage notes payable | 5.81% due February 2021
Notes Payable [Line Items]
Interest rate	5.81%
Fixed rate mortgages	$ 6,943,000	7,325,000
Fixed rate mortgage notes payable | 5.81% due February 2021 | Jamestown Place
Notes Payable [Line Items]
Principal and interest payments	66,000
Balloon payment to be paid	$ 6,100,000
Amortization period	25 years
Amortization of principal	$ 381,700
Fixed rate mortgage notes payable | 6.01% due August 2021
Notes Payable [Line Items]
Interest rate	6.01%
Fixed rate mortgages	$ 5,480,000	5,649,000
Fixed rate mortgage notes payable | 6.01% due August 2021 | Hunt Club Corners
Notes Payable [Line Items]
Principal and interest payments	42,000
Balloon payment to be paid	$ 5,000,000
Amortization period	30 years
Amortization of principal	$ 169,300
Fixed rate mortgage notes payable | 5.62% due June 2022
Notes Payable [Line Items]
Interest rate	5.62%
Fixed rate mortgages	$ 31,723,000	32,673,000
Fixed rate mortgage notes payable | 5.62% due June 2022 | Landsowne Town Center
Notes Payable [Line Items]
Principal and interest payments	230,000
Balloon payment to be paid	$ 28,200,000
Amortization period	30 years
Amortization of principal	$ 949,600
Fixed rate mortgage notes payable | 6.08% due September 2022
Notes Payable [Line Items]
Interest rate	6.08%
Fixed rate mortgages	$ 9,728,000	9,999,000
Fixed rate mortgage notes payable | 6.08% due September 2022 | Orchard Park
Notes Payable [Line Items]
Principal and interest payments	73,000
Balloon payment to be paid	$ 8,600,000
Amortization period	30 years
Amortization of principal	$ 270,300
Fixed rate mortgage notes payable | 6.43% due April 2023
Notes Payable [Line Items]
Interest rate	6.43%
Fixed rate mortgages	$ 10,609,000	10,877,000
Fixed rate mortgage notes payable | 6.43% due April 2023 | BJs Wholesale
Notes Payable [Line Items]
Principal and interest payments	80,000
Balloon payment to be paid	$ 9,300,000
Amortization period	30 years
Amortization of principal	$ 268,400
Fixed rate mortgage notes payable | 6.28% due February 2024
Notes Payable [Line Items]
Interest rate	6.28%
Fixed rate mortgages	$ 11,702,000	12,577,000
Fixed rate mortgage notes payable | 6.28% due February 2024 | Great Falls Shopping Center
Notes Payable [Line Items]
Principal and interest payments	138,000
Balloon payment to be paid	$ 6,300,000
Amortization period	26 years
Amortization of principal	$ 874,800
Number of notes | note	3
Fixed rate mortgage notes payable | 7.35% due June 2024
Notes Payable [Line Items]
Interest rate	7.35%
Fixed rate mortgages	$ 14,952,000	15,452,000
Fixed rate mortgage notes payable | 7.35% due June 2024 | Leesburg Pike
Notes Payable [Line Items]
Principal and interest payments	135,000
Balloon payment to be paid	$ 11,500,000
Amortization period	25 years
Amortization of principal	$ 499,800
Fixed rate mortgage notes payable | 7.60% due June 2024
Notes Payable [Line Items]
Interest rate	7.60%
Fixed rate mortgages	$ 13,013,000	13,438,000
Fixed rate mortgage notes payable | 7.60% due June 2024 | Village Center
Notes Payable [Line Items]
Principal and interest payments	119,000
Balloon payment to be paid	$ 10,100,000
Amortization period	25 years
Amortization of principal	$ 424,700
Fixed rate mortgage notes payable | 7.02% due July 2024
Notes Payable [Line Items]
Interest rate	7.02%
Fixed rate mortgages	$ 23,198,000	23,873,000
Fixed rate mortgage notes payable | 7.02% due July 2024 | White Oak Shopping Center
Notes Payable [Line Items]
Principal and interest payments	193,000
Balloon payment to be paid	$ 18,500,000
Amortization period	24 years 4 months 24 days
Loan amount				$ 10,500,000
Amortization of principal	$ 675,200
Fixed rate mortgage notes payable | 7.45% due July 2024
Notes Payable [Line Items]
Interest rate	7.45%
Fixed rate mortgages	$ 27,222,000	28,115,000
Fixed rate mortgage notes payable | 7.45% due July 2024 | Avenel Business Park
Notes Payable [Line Items]
Principal and interest payments	246,000
Balloon payment to be paid	$ 20,900,000
Amortization period	25 years
Amortization of principal	$ 893,200
Fixed rate mortgage notes payable | 7.30% due January 2025
Notes Payable [Line Items]
Interest rate	7.30%
Fixed rate mortgages	$ 27,168,000	28,025,000
Fixed rate mortgage notes payable | 7.30% due January 2025 | Ashburn Village
Notes Payable [Line Items]
Principal and interest payments	240,000
Balloon payment to be paid	$ 20,500,000
Amortization period	25 years
Amortization of principal	$ 858,000
Fixed rate mortgage notes payable | 6.18% due January 2026
Notes Payable [Line Items]
Interest rate	6.18%
Fixed rate mortgages	$ 14,086,000	14,537,000
Fixed rate mortgage notes payable | 6.18% due January 2026 | Ravenwood
Notes Payable [Line Items]
Principal and interest payments	111,000
Balloon payment to be paid	$ 10,100,000
Amortization period	25 years
Amortization of principal	$ 451,200
Fixed rate mortgage notes payable | 5.31% due April 2026
Notes Payable [Line Items]
Interest rate	5.31%
Fixed rate mortgages	$ 102,310,000	105,817,000
Fixed rate mortgage notes payable | 5.31% due April 2026 | Clarendon Center
Notes Payable [Line Items]
Principal and interest payments	753,000
Balloon payment to be paid	$ 70,500,000
Amortization period	25 years
Amortization of principal	$ 3,500,000
Fixed rate mortgage notes payable | 4.30% due October 2026
Notes Payable [Line Items]
Interest rate	4.30%
Fixed rate mortgages	$ 30,888,000	32,016,000
Fixed rate mortgage notes payable | 4.30% due October 2026 | Severna Park Market Place
Notes Payable [Line Items]
Principal and interest payments	207,000
Balloon payment to be paid	$ 20,300,000
Amortization period	25 years
Amortization of principal	$ 1,100,000
Fixed rate mortgage notes payable | 4.53% due November 2026
Notes Payable [Line Items]
Interest rate	4.53%
Fixed rate mortgages	$ 35,258,000	36,507,000
Fixed rate mortgage notes payable | 4.53% due November 2026 | Kentlands Square II
Notes Payable [Line Items]
Principal and interest payments	240,000
Balloon payment to be paid	$ 23,100,000
Amortization period	25 years
Amortization of principal	$ 1,200,000
Fixed rate mortgage notes payable | 4.70% due December 2026
Notes Payable [Line Items]
Interest rate	4.70%
Fixed rate mortgages	$ 16,515,000	17,086,000
Fixed rate mortgage notes payable | 4.70% due December 2026 | Cranberry Square
Notes Payable [Line Items]
Principal and interest payments	113,000
Balloon payment to be paid	$ 10,900,000
Amortization period	25 years
Amortization of principal	$ 570,500
Fixed rate mortgage notes payable | 5.84% due May 2027
Notes Payable [Line Items]
Interest rate	5.84%
Fixed rate mortgages	$ 62,630,000	64,472,000
Fixed rate mortgage notes payable | 5.84% due May 2027 | Seven Corners
Notes Payable [Line Items]
Principal and interest payments	463,200
Balloon payment to be paid	$ 42,300,000
Amortization period	25 years
Loan amount	$ 73,000,000
Amortization of principal	$ 1,800,000
Fixed rate mortgage notes payable | 4.04% due April 2028
Notes Payable [Line Items]
Interest rate	4.04%
Fixed rate mortgages	$ 15,345,000	15,859,000
Fixed rate mortgage notes payable | 4.04% due April 2028 | Hampshire Langley
Notes Payable [Line Items]
Principal and interest payments	95,400
Balloon payment to be paid	$ 9,500,000
Amortization period	25 years
Amortization of principal	$ 513,700
Fixed rate mortgage notes payable | 3.51% due June 2028
Notes Payable [Line Items]
Interest rate	3.51%
Fixed rate mortgages	$ 38,120,000	39,968,000
Fixed rate mortgage notes payable | 3.51% due June 2028 | Beacon Center
Notes Payable [Line Items]
Balloon payment to be paid	$ 17,100,000
Amortization period	20 years
Amortization of principal	$ 1,800,000
Fixed rate mortgage notes payable | 3.99% due September 2028
Notes Payable [Line Items]
Interest rate	3.99%
Fixed rate mortgages	$ 15,547,000	16,055,000
Fixed rate mortgage notes payable | 3.99% due September 2028 | Seabreeze Plaza
Notes Payable [Line Items]
Principal and interest payments	94,900
Balloon payment to be paid	$ 9,500,000
Amortization period	25 years
Amortization of principal	$ 507,600
Fixed rate mortgage notes payable | 3.69% Due March 2030
Notes Payable [Line Items]
Interest rate	3.69%
Fixed rate mortgages	$ 27,060,000	27,884,000
Fixed rate mortgage notes payable | 3.69% Due March 2030 | Shops at Fairfax and Boulevard
Notes Payable [Line Items]
Principal and interest payments	153,300
Balloon payment to be paid	$ 15,500,000
Amortization period	25 years
Amortization of principal	$ 824,000
Fixed rate mortgage notes payable | 3.99% Due April 2030
Notes Payable [Line Items]
Interest rate	3.99%
Fixed rate mortgages	$ 14,526,000	14,950,000
Fixed rate mortgage notes payable | 3.99% Due April 2030 | Northrock
Notes Payable [Line Items]
Principal and interest payments	84,400
Balloon payment to be paid	$ 8,400,000
Amortization period	25 years
Amortization of principal	$ 423,600
Fixed rate mortgage notes payable | 3.39% due January 2032
Notes Payable [Line Items]
Interest rate	3.39%
Fixed rate mortgages	$ 38,076,000	39,140,000
Fixed rate mortgage notes payable | 3.39% due January 2032 | Burtonsville Town Square
Notes Payable [Line Items]
Principal and interest payments	197,900
Balloon payment to be paid	$ 20,300,000
Amortization period	25 years
Amortization of principal	$ 1,100,000
Fixed rate mortgage notes payable | 4.88% due September 2032
Notes Payable [Line Items]
Interest rate	4.88%
Fixed rate mortgages	$ 69,691,000	71,211,000
Fixed rate mortgage notes payable | 4.88% due September 2032 | Park Van Ness
Notes Payable [Line Items]
Principal and interest payments	413,500
Balloon payment to be paid	$ 39,600,000
Amortization period	25 years
Amortization of principal	$ 1,500,000
Fixed rate mortgages			$ 71,580,000
Fixed rate mortgage notes payable | 3.75% due December 2032
Notes Payable [Line Items]
Interest rate	3.75%
Fixed rate mortgages	$ 58,523,000	60,000,000
Fixed rate mortgage notes payable | 3.75% due December 2032 | Washington Square
Notes Payable [Line Items]
Principal and interest payments	308,500
Balloon payment to be paid	$ 31,100,000
Amortization period	25 years
Amortization of principal	$ 1,500,000
Fixed rate mortgage notes payable | 4.41% mortgage maturing 2033
Notes Payable [Line Items]
Interest rate	4.41%
Fixed rate mortgages	$ 31,941,000	0
Fixed rate mortgage notes payable | 4.41% mortgage maturing 2033 | Broadlands Village
Notes Payable [Line Items]
Principal and interest payments	176,200
Balloon payment to be paid	$ 17,300,000
Amortization period	25 years
Amortization of principal	$ 58,600
Fixed rate mortgage notes payable | 4.69% fixed rate loan maturing in 2034
Notes Payable [Line Items]
Interest rate	4.69%
Fixed rate mortgages	$ 22,900,000	0
Fixed rate mortgage notes payable | 4.69% fixed rate loan maturing in 2034 | The Glen
Notes Payable [Line Items]
Principal and interest payments	129,800
Balloon payment to be paid	$ 12,500,000
Amortization period	25 years
Fixed rate mortgage notes payable | 8.00% due April 2034
Notes Payable [Line Items]
Interest rate	8.00%
Fixed rate mortgages	$ 11,781,000	11,613,000
Fixed rate mortgage notes payable | 8.00% due April 2034 | Olney
Notes Payable [Line Items]
Principal and interest payments	60,400
Balloon payment to be paid	$ 14,700,000
Fixed rate increase on note	1.50%
Interest rate	8.00%
Negative amortization	$ (168,600)
Fixed rate mortgage notes payable | 4.67% Construction To Permanent Loan Due 2035
Notes Payable [Line Items]
Interest rate	4.67%
Fixed rate mortgages	$ 23,332,000	$ 0
Fixed rate mortgage notes payable | 4.67% Construction To Permanent Loan Due 2035 | Glebe Road
Notes Payable [Line Items]
Principal and interest payments	$ 887,900
Amortization period	25 years
Fixed rate mortgages			$ 157,000,000
Variable rate loans payable
Notes Payable [Line Items]
Interest rate spread on LIBOR	3.84%
Variable rate loans payable | Metro Pike Center Bank Loan
Notes Payable [Line Items]
Interest rate spread on LIBOR	1.65%
Variable rate loans payable | Metro Pike Center Bank Loan | Metro Pike Center
Notes Payable [Line Items]
Principal and interest payments	$ 48,000
Balloon payment to be paid	14,200,000
New Facility | Line of Credit
Notes Payable [Line Items]
Line of credit facility, maximum borrowing capacity	400,000,000
Revolving Credit Facility | New Facility | Line of Credit
Notes Payable [Line Items]
Line of credit facility, maximum borrowing capacity	$ 325,000,000
Debt maturity extension period	1 year
Debt instrument fee	0.15%
Interest rate spread on LIBOR	1.35%
Term Facility | New Facility | Line of Credit
Notes Payable [Line Items]
Line of credit facility, maximum borrowing capacity	$ 75,000,000
Interest rate spread on LIBOR	1.30%

Mortgage Notes Payable, Revol_6

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, 2018	Dec. 31, 2017
Balloon Payments
2,019	$ 60,794
2,020	61,163
2,021	11,012
2,022	83,502
2,023	84,225
Thereafter	480,132
Balloon Payments	780,828
Scheduled Principal Amortization
2,019	2,257
2,020	28,042
2,021	27,815
2,022	28,381
2,023	28,745
Thereafter	136,121
Scheduled Principal Amortization	251,361
Total
2,019	63,051
2,020	89,205
2,021	38,827
2,022	111,883
2,023	112,970
Thereafter	616,253
Principal amount	1,032,189	$ 965,500
Unamortized deferred debt costs	10,343	$ 6,900
Net	$ 1,021,846

Mortgage Notes Payable, Revol_7

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, 2018	Dec. 31, 2017	Dec. 31, 2016
Debt Disclosure [Abstract]
Interest incurred	$ 49,652	$ 49,322	$ 46,867
Amortization of deferred debt costs	1,610	1,392	1,343
Capitalized interest	(6,222)	(3,489)	(2,527)
Total	$ 45,040	$ 47,225	$ 45,683

Lease Agreements - Additional I

Lease Agreements - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Leases [Abstract]
Base rent (including straight-line rent)	$ 184,684	$ 181,141	$ 172,381
Expense recoveries	35,500	35,300	34,300
Percentage rent	$ 994	$ 1,458	$ 1,379

Lease Agreements - Future Contr

Lease Agreements - Future Contractual Payments Under Noncancelable Leases (Detail) $ in Thousands	Dec. 31, 2018USD ($)
Leases [Abstract]
2,019	$ 163,489
2,020	146,425
2,021	125,372
2,022	101,778
2,023	79,903
Thereafter	244,801
Total future contractual payments	$ 861,768

Long Term Lease Obligations - A

Long Term Lease Obligations - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2018USD ($)property	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Leases Disclosure [Line Items]
Number of properties subject to noncancelable long-term lease | property	0
Minimum rental obligations		$ 10,500	$ 159,000
Rent expense	$ 779,800	$ 774,700	$ 843,300
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_2

Equity and Noncontrolling Interest - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands, shares in Millions	Feb. 22, 2018	Jan. 23, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Class of Stock [Line Items]
Income attributable to noncontrolling interests			$ 12,505	$ 12,411	$ 11,441
Series D Cumulative Redeemable Preferred Stock
Class of Stock [Line Items]
Depositary shares outstanding (in shares)		3
Net proceeds from shares sold		$ 72,600
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 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
Percentage of redeemable preferred stock			6.875%
Stock redeemed during period (in shares)	3
Depository shares to cumulative redeemable preferred stock ratio			1.00%
Dividend rate on preferred stock			6.875%

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Detail)	May 09, 2018shares	Dec. 08, 2016	May 31, 2018ashares	Aug. 31, 2016a	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
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					$ 345,900	$ 349,500	$ 329,000
Deferred compensation, employee contribution, percentage					2.00%
Deferred compensation, employer contribution, percentage					3	3	3
Deferred compensation, company contribution, amount					$ 282,500	$ 228,500	$ 250,800
Deferred compensation, cumulative unfunded liability					2,700,000	2,400,000
Ancillary costs and expenses					8,400,000	8,100,000	7,200,000
Liability due to the Saul Organization for the company's share of these ancillary costs and expenses					933,400	993,200
Automatic renewal period		12 months
Insurance commissions and fees expense					$ 407,900	$ 288,400	$ 360,500
Area of real estate property (in square feet) | a			13,700	13,700
Ashbrook Marketplace | BF Saul Real Estate Investment Trust
Related Party Transaction [Line Items]
Limited partnership units issued (in shares) | shares	176,680		176,680

Stock Option Plan - Additional

Stock Option Plan - Additional Information (Detail)

May 11, 2018USD ($)person$ / sharesshares

May 05, 2017USD ($)person$ / sharesshares

May 06, 2016USD ($)person$ / sharesshares

May 08, 2015USD ($)person$ / sharesshares

May 09, 2014USD ($)person$ / sharesshares

May 10, 2013USD ($)person$ / sharesshares

May 04, 2012USD ($)person$ / sharesshares

May 13, 2011USD ($)person$ / sharesshares

May 07, 2010USD ($)person$ / sharesshares

Apr. 24, 2009USD ($)person$ / sharesshares

Dec. 31, 2018USD ($)$ / shares

Dec. 31, 2017$ / shares

Dec. 31, 2016$ / shares

Dec. 31, 2004shares

Dec. 31, 1993shares

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Exercise price of options (in usd per share) | $ / shares

$ 49.46

$ 59.41

$ 57.74

Fair value stock option grant | $

$ 13,060,000

the 1993 Plan | Stock options

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Authorized shares for a grant (in shares)

400,000

Amended 2004 Plan | Stock options

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Authorized shares for a grant (in shares)

2,000,000

Amended 2004 Plan | Stock options | Director

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Authorized shares for a grant (in shares)

200,000

2009 Options

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Exercise price of options (in usd per share) | $ / shares

$ 32.68

Fair value stock option grant | $

$ 222,950

2009 Options | Director

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Number of individuals granted options | person

13

2009 Options | Stock options | Officer

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Options granted to purchase stocks (in shares)

0

2009 Options | Stock options | Director

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Options granted to purchase stocks (in shares)

32,500

2010 Options

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Exercise price of options (in usd per share) | $ / shares

$ 38.76

Fair value stock option grant | $

$ 287,950

2010 Options | Director

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Number of individuals granted options | person

13

2010 Options | Stock options | Officer

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Options granted to purchase stocks (in shares)

0

2010 Options | Stock options | Director

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Options granted to purchase stocks (in shares)

32,500

2011 Options

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Exercise price of options (in usd per share) | $ / shares

$ 41.82

Fair value stock option grant | $

$ 1,600,000

2011 Options | Officer

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Number of individuals granted options | person

15

Fair value stock option grant | $

$ 1,300,000

Options vested

25.00%

2011 Options | Director

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Number of individuals granted options | person

13

Fair value stock option grant | $

$ 297,375

2011 Options | Stock options

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Options granted to purchase stocks (in shares)

195,000

2011 Options | Stock options | Officer

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Option vesting period

4 years

2011 Options | Incentive stock option

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Options granted to purchase stocks (in shares)

65,300

2011 Options | Nonqualified stock options

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Options granted to purchase stocks (in shares)

129,700

2012 Options

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Exercise price of options (in usd per share) | $ / shares

$ 39.29

Fair value stock option grant | $

$ 1,700,000

2012 Options | Officer

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Number of individuals granted options | person

15

Fair value stock option grant | $

$ 1,400,000

Options vested

25.00%

2012 Options | Director

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Number of individuals granted options | person

14

Fair value stock option grant | $

$ 257,250

2012 Options | Stock options

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Options granted to purchase stocks (in shares)

277,500

2012 Options | Stock options | Officer

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Option vesting period

4 years

2012 Options | Incentive stock option

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Options granted to purchase stocks (in shares)

26,157

2012 Options | Nonqualified stock options

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Options granted to purchase stocks (in shares)

251,343

2013 Options

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Number of individuals granted options | person

15

Exercise price of options (in usd per share) | $ / shares

$ 44.42

Fair value stock option grant | $

$ 1,500,000

2013 Options | Officer

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Fair value stock option grant | $

$ 1,200,000

Options vested

25.00%

2013 Options | Director

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Number of individuals granted options | person

14

Fair value stock option grant | $

$ 278,250

2013 Options | Stock options

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Options granted to purchase stocks (in shares)

237,500

2013 Options | Stock options | Officer

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Option vesting period

4 years

2013 Options | Incentive stock option

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Options granted to purchase stocks (in shares)

35,592

2013 Options | Nonqualified stock options

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Options granted to purchase stocks (in shares)

201,908

2014 Options

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Exercise price of options (in usd per share) | $ / shares

$ 47.03

Fair value stock option grant | $

$ 1,300,000

2014 Options | Officer

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Number of individuals granted options | person

18

Fair value stock option grant | $

$ 1,200,000

Options vested

25.00%

2014 Options | Director

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Number of individuals granted options | person

12

Fair value stock option grant | $

$ 109,500

2014 Options | Stock options

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Options granted to purchase stocks (in shares)

200,000

2014 Options | Stock options | Officer

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Option vesting period

4 years

2014 Options | Incentive stock option

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Options granted to purchase stocks (in shares)

29,300

2014 Options | Nonqualified stock options

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Options granted to purchase stocks (in shares)

170,700

2015 Options

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Exercise price of options (in usd per share) | $ / shares

$ 51.07

Fair value stock option grant | $

$ 1,570,000

2015 Options | Officer

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Number of individuals granted options | person

19

Fair value stock option grant | $

$ 1,440,000

Options vested

25.00%

2015 Options | Director

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Number of individuals granted options | person

14

Fair value stock option grant | $

$ 125,300

2015 Options | Stock options

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Options granted to purchase stocks (in shares)

225,000

2015 Options | Stock options | Officer

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Option vesting period

4 years

2015 Options | Incentive stock option

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Options granted to purchase stocks (in shares)

33,690

2015 Options | Nonqualified stock options

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Options granted to purchase stocks (in shares)

191,310

2016 Options

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Exercise price of options (in usd per share) | $ / shares

$ 57.74

Fair value stock option grant | $

$ 1,200,000

2016 Options | Officer

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Number of individuals granted options | person

19

Fair value stock option grant | $

$ 1,000,000

Options vested

25.00%

2016 Options | Director

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Number of individuals granted options | person

13

Fair value stock option grant | $

$ 151,100

2016 Options | Stock options

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Options granted to purchase stocks (in shares)

226,500

2016 Options | Stock options | Officer

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Option vesting period

4 years

2016 Options | Incentive stock option

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Options granted to purchase stocks (in shares)

24,248

2016 Options | Nonqualified stock options

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Options granted to purchase stocks (in shares)

202,252

2017 Options

Share-based Compensation, Shares Authorized under Stock Option Plans, 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 Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Number of individuals granted options | person

20

Fair value stock option grant | $

$ 1,200,000

Options vested

25.00%

2017 Options | Director

Share-based Compensation, Shares Authorized under Stock Option Plans, 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 Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Options granted to purchase stocks (in shares)

232,500

2017 Options | Stock options | Officer

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Option vesting period

4 years

2017 Options | Incentive stock option

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Options granted to purchase stocks (in shares)

21,492

2017 Options | Nonqualified stock options

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Options granted to purchase stocks (in shares)

211,008

2018 Options

Share-based Compensation, Shares Authorized under Stock Option Plans, 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 Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Number of individuals granted options | person

22

Fair value stock option grant | $

$ 1,200,000

Options vested

25.00%

2018 Options | Director

Share-based Compensation, Shares Authorized under Stock Option Plans, 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 Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Options granted to purchase stocks (in shares)

245,000

2018 Options | Stock options | Officer

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Option vesting period

4 years

2018 Options | Incentive stock option

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Options granted to purchase stocks (in shares)

25,914

2018 Options | Nonqualified stock options

Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]

Options granted to purchase stocks (in shares)

219,086

Stock Option Plan - Stock Optio

Stock Option Plan - Stock Options Issued (Detail)	12 Months Ended
	Dec. 31, 2018USD ($)$ / sharesshares	Dec. 31, 2017USD ($)$ / sharesshares	Dec. 31, 2016USD ($)$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total grant (in shares)	1,904,000
Vested (in shares)	1,174,500
Exercised (in shares)	566,081
Forfeited (in shares)	223,750
Exercisable at December 31 (in shares)	600,919	430,945	375,255
Remaining unexercised (in shares)	1,114,169
Exercise price (in usd per share) | $ / shares	$ 42.98	$ 46.97	$ 45.59
Total value at grant date | $	$ 13,060,000
Estimated forfeitures | $	1,843,000
Expensed in previous years | $	4,648,000
Allocated share based compensation | $	1,558,000	$ 1,448,000	$ 1,348,000
Future expense | $	2,215,000
Directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share based compensation | $	$ 108,800	130,700	150,100
Directors | 4/24/2009
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total grant (in shares)	32,500
Vested (in shares)	32,500
Exercised (in shares)	30,000
Forfeited (in shares)	0
Exercisable at December 31 (in shares)	2,500
Remaining unexercised (in shares)	2,500
Exercise price (in usd per share) | $ / shares	$ 32.68
Volatility	0.344
Expected life (years)	6 years
Assumed yield	4.54%
Risk-free rate	2.19%
Total value at grant date | $	$ 223,000
Expensed in previous years | $	223,000
Allocated share based compensation | $	0	0	0
Future expense | $	$ 0
Directors | 5/7/2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total grant (in shares)	32,500
Vested (in shares)	32,500
Exercised (in shares)	27,500
Forfeited (in shares)	2,500
Exercisable at December 31 (in shares)	2,500
Remaining unexercised (in shares)	2,500
Exercise price (in usd per share) | $ / shares	$ 38.76
Volatility	0.369
Expected life (years)	5 years
Assumed yield	4.23%
Risk-free rate	2.17%
Total value at grant date | $	$ 288,000
Expensed in previous years | $	288,000
Allocated share based compensation | $	0	0	0
Future expense | $	$ 0
Directors | 5/13/2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total grant (in shares)	32,500
Vested (in shares)	32,500
Exercised (in shares)	25,000
Forfeited (in shares)	2,500
Exercisable at December 31 (in shares)	5,000
Remaining unexercised (in shares)	5,000
Exercise price (in usd per share) | $ / shares	$ 41.82
Volatility	0.358
Expected life (years)	5 years
Assumed yield	4.16%
Risk-free rate	1.86%
Total value at grant date | $	$ 298,000
Expensed in previous years | $	298,000
Allocated share based compensation | $	0	0	0
Future expense | $	$ 0
Directors | 5/4/2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total grant (in shares)	35,000
Vested (in shares)	35,000
Exercised (in shares)	25,000
Forfeited (in shares)	0
Exercisable at December 31 (in shares)	10,000
Remaining unexercised (in shares)	10,000
Exercise price (in usd per share) | $ / shares	$ 39.29
Volatility	0.348
Expected life (years)	5 years
Assumed yield	4.61%
Risk-free rate	0.78%
Total value at grant date | $	$ 257,000
Expensed in previous years | $	257,000
Allocated share based compensation | $	0	0	0
Future expense | $	$ 0
Directors | 5/10/2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total grant (in shares)	35,000
Vested (in shares)	35,000
Exercised (in shares)	22,500
Forfeited (in shares)	0
Exercisable at December 31 (in shares)	12,500
Remaining unexercised (in shares)	12,500
Exercise price (in usd per share) | $ / shares	$ 44.42
Volatility	0.333
Expected life (years)	5 years
Assumed yield	4.53%
Risk-free rate	0.82%
Total value at grant date | $	$ 278,000
Expensed in previous years | $	278,000
Allocated share based compensation | $	0	0	0
Future expense | $	$ 0
Directors | 5/9/2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total grant (in shares)	30,000
Vested (in shares)	30,000
Exercised (in shares)	17,500
Forfeited (in shares)	0
Exercisable at December 31 (in shares)	12,500
Remaining unexercised (in shares)	12,500
Exercise price (in usd per share) | $ / shares	$ 47.03
Volatility	0.173
Expected life (years)	5 years
Assumed yield	4.48%
Risk-free rate	1.63%
Total value at grant date | $	$ 110,000
Expensed in previous years | $	110,000
Allocated share based compensation | $	0	0	0
Future expense | $	$ 0
Directors | 5/8/2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total grant (in shares)	35,000
Vested (in shares)	35,000
Exercised (in shares)	12,500
Forfeited (in shares)	0
Exercisable at December 31 (in shares)	22,500
Remaining unexercised (in shares)	22,500
Exercise price (in usd per share) | $ / shares	$ 51.07
Volatility	0.166
Expected life (years)	5 years
Assumed yield	4.54%
Risk-free rate	1.50%
Total value at grant date | $	$ 125,000
Expensed in previous years | $	125,000
Allocated share based compensation | $	0	0	0
Future expense | $	$ 0
Directors | 5/6/2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total grant (in shares)	32,500
Vested (in shares)	32,500
Exercised (in shares)	7,500
Forfeited (in shares)	0
Exercisable at December 31 (in shares)	25,000
Remaining unexercised (in shares)	25,000
Exercise price (in usd per share) | $ / shares	$ 57.74
Volatility	0.166
Expected life (years)	5 years
Assumed yield	3.75%
Risk-free rate	1.23%
Total value at grant date | $	$ 151,000
Expensed in previous years | $	0
Allocated share based compensation | $	0	0	151,000
Future expense | $	$ 0
Directors | 5/5/2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total grant (in shares)	27,500
Vested (in shares)	27,500
Exercised (in shares)	0
Forfeited (in shares)	2,500
Exercisable at December 31 (in shares)	25,000
Remaining unexercised (in shares)	25,000
Exercise price (in usd per share) | $ / shares	$ 59.41
Volatility	0.173
Expected life (years)	5 years
Assumed yield	3.45%
Risk-free rate	1.89%
Total value at grant date | $	$ 166,000
Expensed in previous years | $	0
Allocated share based compensation | $	0	166,000	0
Future expense | $	$ 0
Directors | 5/11/2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total grant (in shares)	27,500
Vested (in shares)	27,500
Exercised (in shares)	2,500
Forfeited (in shares)	0
Exercisable at December 31 (in shares)	25,000
Remaining unexercised (in shares)	25,000
Exercise price (in usd per share) | $ / shares	$ 49.46
Volatility	0.192
Expected life (years)	5 years
Assumed yield	3.70%
Risk-free rate	2.84%
Total value at grant date | $	$ 169,000
Expensed in previous years | $	0
Allocated share based compensation | $	169,000	0	0
Future expense | $	$ 0
Directors | Subtotals
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total grant (in shares)	320,000
Vested (in shares)	320,000
Exercised (in shares)	170,000
Forfeited (in shares)	7,500
Exercisable at December 31 (in shares)	142,500
Remaining unexercised (in shares)	142,500
Total value at grant date | $	$ 2,065,000
Expensed in previous years | $	1,579,000
Allocated share based compensation | $	169,000	166,000	151,000
Future expense | $	$ 0
Officers | 5/13/2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total grant (in shares)	162,500
Vested (in shares)	118,750
Exercised (in shares)	103,750
Forfeited (in shares)	43,750
Exercisable at December 31 (in shares)	15,000
Remaining unexercised (in shares)	15,000
Exercise price (in usd per share) | $ / shares	$ 41.82
Volatility	0.330
Expected life (years)	8 years
Assumed yield	4.81%
Risk-free rate	2.75%
Total value at grant date | $	$ 1,367,000
Estimated forfeitures | $	368,000
Expensed in previous years | $	999,000
Allocated share based compensation | $	0	0	0
Future expense | $	$ 0
Weighted average term of remaining future expense	2 years 6 months 11 days
Officers | 5/4/2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total grant (in shares)	242,500
Vested (in shares)	107,500
Exercised (in shares)	92,455
Forfeited (in shares)	135,000
Exercisable at December 31 (in shares)	15,045
Remaining unexercised (in shares)	15,045
Exercise price (in usd per share) | $ / shares	$ 39.29
Volatility	0.315
Expected life (years)	8 years
Assumed yield	5.28%
Risk-free rate	1.49%
Total value at grant date | $	$ 1,518,000
Estimated forfeitures | $	845,000
Expensed in previous years | $	576,000
Allocated share based compensation | $	0	0	97,000
Future expense | $	$ 0
Officers | 5/10/2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total grant (in shares)	202,500
Vested (in shares)	171,875
Exercised (in shares)	129,375
Forfeited (in shares)	30,625
Exercisable at December 31 (in shares)	42,500
Remaining unexercised (in shares)	42,500
Exercise price (in usd per share) | $ / shares	$ 44.42
Volatility	0.304
Expected life (years)	8 years
Assumed yield	5.12%
Risk-free rate	1.49%
Total value at grant date | $	$ 1,401,000
Estimated forfeitures | $	212,000
Expensed in previous years | $	762,000
Allocated share based compensation | $	0	158,000	269,000
Future expense | $	$ 0
Officers | 5/9/2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total grant (in shares)	170,000
Vested (in shares)	168,125
Exercised (in shares)	46,126
Forfeited (in shares)	1,875
Exercisable at December 31 (in shares)	121,999
Remaining unexercised (in shares)	121,999
Exercise price (in usd per share) | $ / shares	$ 47.03
Volatility	0.306
Expected life (years)	7 years
Assumed yield	4.89%
Risk-free rate	2.17%
Total value at grant date | $	$ 1,350,000
Estimated forfeitures | $	15,000
Expensed in previous years | $	492,000
Allocated share based compensation | $	252,000	295,000	296,000
Future expense | $	$ 0
Officers | 5/8/2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total grant (in shares)	190,000
Vested (in shares)	140,625
Exercised (in shares)	20,625
Forfeited (in shares)	3,125
Exercisable at December 31 (in shares)	120,000
Remaining unexercised (in shares)	166,250
Exercise price (in usd per share) | $ / shares	$ 51.07
Volatility	0.298
Expected life (years)	7 years
Assumed yield	4.94%
Risk-free rate	1.89%
Total value at grant date | $	$ 1,585,000
Estimated forfeitures | $	142,000
Expensed in previous years | $	240,000
Allocated share based compensation | $	361,000	361,000	360,000
Future expense | $	$ 121,000
Officers | 5/6/2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total grant (in shares)	194,000
Vested (in shares)	96,375
Exercised (in shares)	3,750
Forfeited (in shares)	1,875
Exercisable at December 31 (in shares)	92,625
Remaining unexercised (in shares)	188,375
Exercise price (in usd per share) | $ / shares	$ 57.74
Volatility	0.185
Expected life (years)	7 years
Assumed yield	3.80%
Risk-free rate	1.55%
Total value at grant date | $	$ 1,137,000
Estimated forfeitures | $	86,000
Expensed in previous years | $	0
Allocated share based compensation | $	263,000	263,000	175,000
Future expense | $	$ 350,000
Officers | 5/5/2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total grant (in shares)	205,000
Vested (in shares)	51,250
Exercised (in shares)	0
Forfeited (in shares)	0
Exercisable at December 31 (in shares)	51,250
Remaining unexercised (in shares)	205,000
Exercise price (in usd per share) | $ / shares	$ 59.41
Volatility	0.170
Expected life (years)	7 years
Assumed yield	3.50%
Risk-free rate	2.17%
Total value at grant date | $	$ 1,324,000
Estimated forfeitures | $	92,000
Expensed in previous years | $	0
Allocated share based compensation | $	308,000	205,000	0
Future expense | $	$ 719,000
Officers | 5/11/2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total grant (in shares)	217,500
Vested (in shares)	0
Exercised (in shares)	0
Forfeited (in shares)	0
Exercisable at December 31 (in shares)	0
Remaining unexercised (in shares)	217,500
Exercise price (in usd per share) | $ / shares	$ 49.46
Volatility	0.177
Expected life (years)	7 years
Assumed yield	3.75%
Risk-free rate	2.94%
Total value at grant date | $	$ 1,313,000
Estimated forfeitures | $	83,000
Expensed in previous years | $	0
Allocated share based compensation | $	205,000	0	0
Future expense | $	$ 1,025,000
Officers | Subtotals
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total grant (in shares)	1,584,000
Vested (in shares)	854,500
Exercised (in shares)	396,081
Forfeited (in shares)	216,250
Exercisable at December 31 (in shares)	458,419
Remaining unexercised (in shares)	971,669
Total value at grant date | $	$ 10,995,000
Estimated forfeitures | $	1,843,000
Expensed in previous years | $	3,069,000
Allocated share based compensation | $	1,389,000	$ 1,282,000	$ 1,197,000
Future expense | $	$ 2,215,000

Stock Option Plan - Summary of

Stock Option Plan - Summary of Option Activity (Detail) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Shares
Outstanding at January 1 (in shares)	913,320	833,630	860,274
Granted (in shares)	245,000	232,500	226,500
Exercised (in shares)	(39,151)	(149,060)	(246,894)
Expired/Forfeited (in shares)	(5,000)	(3,750)	(6,250)
Outstanding December 31 (in shares)	1,114,169	913,320	833,630
Options exercisable (in shares)	600,919	430,945	375,255
Weighted Average Exercise Price
Outstanding at January 1 (in usd per share)	$ 52.80	$ 49.92	$ 46.58
Granted (in usd per share)	49.46	59.41	57.74
Exercised (in usd per share)	42.98	46.97	45.59
Expired/Forfeited (in usd per share)	54.78	53.73	45.31
Outstanding December 31 (in usd per share)	52.40	52.80	49.92
Exercisable at December 31 (in usd per share)	$ 50.93	$ 48.94	$ 46.68
Intrinsic value of options exercised	$ 0.5	$ 2.2	$ 3.4
Intrinsic value of options outstanding	0.5
Intrinsic value of options exercisable	$ 0.5
Closing price (in usd per share)	$ 47.22
Weighted average remaining life of options exercisable	6 years 2 months 16 days
Weighted average remaining life of options outstanding	7 years 2 months 19 days

Fair Value of Financial Instr_3

Fair Value of Financial Instruments - Additional Information (Detail) $ in Thousands	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Jun. 30, 2011instrument
Fair Value of Financial Instruments [Line Items]
Interest rate	4.40%	3.90%
Notes payable, fair value	$ 927,000	$ 951,700
Fixed rate mortgages	880,271	897,888
Interest rate swap
Fair Value of Financial Instruments [Line Items]
Fair value of derivative liability	$ 400
Cash flow hedging | Designated as hedging instrument | Interest rate swap
Fair Value of Financial Instruments [Line Items]
Derivative, number of instruments held | instrument			1
Fixed rate mortgage notes payable
Fair Value of Financial Instruments [Line Items]
Interest rate	5.18%
Fixed rate mortgages	$ 910,189	$ 890,393

Fair Value of Financial Instr_4

Fair Value of Financial Instruments - Changes in Fair Value of Swaps (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Increase (decrease) in fair value:
Recognized in earnings	$ (3)	$ 70	$ (6)
Recognized in other comprehensive income	594	812	678
Total	$ 591	$ 882	$ 672

Distributions - Additional Info

Distributions - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	Jan. 31, 2019	Jan. 15, 2019	Jan. 02, 2019	Dec. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Dividends [Line Items]
Common stock issued, discount rate					3.00%
Common stock distributions (in usd per share)					$ 2.08	$ 2.04	$ 1.84
Dividends declared per common share outstanding (in usd per share)				$ 0.53
Distribution to limited partnership unitholders					$ 15,981	$ 15,268	$ 13,533
Dividend Income
Dividends [Line Items]
Common stock distributions (in usd per share)					$ 1.61	$ 1.7	$ 1.75
Return on Invested Capital
Dividends [Line Items]
Return of capital (in usd per share)				$ 0.47	0.47	0.34	0.09
Series C Preferred Stock
Dividends [Line Items]
Preferred stock dividend (in usd per share)					1.72	$ 1.72	$ 1.72
Series D Preferred Stock
Dividends [Line Items]
Preferred stock dividend (in usd per share)					$ 1.05
Subsequent Event
Dividends [Line Items]
Common stock dividend paid	$ 12,000
Distribution to limited partnership unitholders	$ 4,100
Distributions partnership units (in usd per share)	$ 0.53
Preferred stock distributions		$ 3,000
Subsequent Event | Series C Preferred Stock
Dividends [Line Items]
Dividends declared per preferred share outstanding (in usd per share)			$ 0.4297
Subsequent Event | Series D Preferred Stock
Dividends [Line Items]
Dividends declared per preferred share outstanding (in usd per share)			$ 0.3828

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, 2018	Jul. 31, 2018	Apr. 30, 2018	Jan. 31, 2018	Oct. 31, 2017	Jul. 31, 2017	Apr. 30, 2017	Oct. 31, 2016	Jul. 31, 2016	Apr. 30, 2016	Jan. 31, 2016	Jan. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Dividends [Line Items]
Preferred Stockholders													$ 12,402	$ 12,375	$ 12,375
Common Stockholders													46,306	44,576	39,472
Limited Partnership Unitholders													$ 15,981	$ 15,268	$ 13,533
Common Stock Shares Issued (in shares)													572,928	266,011	186,797
Limited Partnership Units Issued (in shares)													107,433	111,351	124,758
October 31
Dividends [Line Items]
Preferred Stockholders	$ 2,953				$ 3,094			$ 3,094
Common Stockholders	11,706				11,221			10,168
Limited Partnership Unitholders	$ 4,062				$ 3,838			$ 3,478
Common Stock Shares Issued (in shares)	216,476				82,991			44,176
Discounted Share Price (in usd per share)	$ 49.34				$ 59.33			$ 57.18
Limited Partnership Units Issued (in shares)	13,867				15,596			30,891
Average Unit Price (in usd per share)	$ 50.20				$ 60.08			$ 57.18
July 31
Dividends [Line Items]
Preferred Stockholders		$ 2,953				$ 3,094			$ 3,094
Common Stockholders		11,590				11,160			10,133
Limited Partnership Unitholders		$ 4,055				$ 3,830			$ 3,465
Common Stock Shares Issued (in shares)		201,500				85,731			39,487
Discounted Share Price (in usd per share)		$ 51.68				$ 57.40			$ 65.64
Limited Partnership Units Issued (in shares)		13,107				16,021			26,897
Average Unit Price (in usd per share)		$ 52.60				$ 58.13			$ 65.64
April 30
Dividends [Line Items]
Preferred Stockholders			$ 2,672				$ 3,094			$ 3,094
Common Stockholders			11,545				11,119			10,029
Limited Partnership Unitholders			$ 3,942				$ 3,810			$ 3,449
Common Stock Shares Issued (in shares)			85,202				51,003			48,854
Discounted Share Price (in usd per share)			$ 47.54				$ 59.64			$ 51.59
Limited Partnership Units Issued (in shares)			42,422				40,623			34,201
Average Unit Price (in usd per share)			$ 47.83				$ 59.96			$ 51.59
January 31
Dividends [Line Items]
Preferred Stockholders				$ 3,824							$ 3,093	$ 3,093
Common Stockholders				11,465							9,142	11,076
Limited Partnership Unitholders				$ 3,922							$ 3,141	$ 3,790
Common Stock Shares Issued (in shares)				69,750							54,280	46,286
Discounted Share Price (in usd per share)				$ 52.71							$ 49.24	$ 61.85
Limited Partnership Units Issued (in shares)				38,037							32,769	39,111
Average Unit Price (in usd per share)				$ 53.03							$ 49.24	$ 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, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Revenue	$ 58,328	$ 57,059	$ 56,293	$ 56,496	$ 56,675	$ 56,237	$ 55,907	$ 58,466	$ 227,904	$ 227,205	$ 217,019
Operating income before loss on early extinguishment of debt, gain on casualty settlement, and noncontrolling interests	15,510	16,692	15,405	14,946	14,416	14,386	14,422	17,374	62,553	60,598	55,713
Gains on sale of property	0	0	509	0	0	0	0	0	509	0	1,013
Net income attributable to Saul Centers, Inc.	12,269	13,155	12,543	12,587	11,560	11,483	11,510	13,704	50,554	48,257	45,279
Net income available to common stockholders	$ 9,316	$ 10,202	$ 9,590	$ 6,856	$ 8,466	$ 8,390	$ 8,416	$ 10,610	$ 35,964	$ 35,882	$ 32,904
Net income available to common stockholders per diluted share (in usd per share)	$ 0.41	$ 0.45	$ 0.43	$ 0.31	$ 0.38	$ 0.38	$ 0.38	$ 0.49	$ 1.60	$ 1.63	$ 1.52

Business Segments - Additional

Business Segments - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2018segment
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, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Revenue	$ 58,328	$ 57,059	$ 56,293	$ 56,496	$ 56,675	$ 56,237	$ 55,907	$ 58,466	$ 227,904	$ 227,205	$ 217,019
Expenses									(56,263)	(55,592)	(53,701)
Income from real estate									171,641	171,613	163,318
Other revenue									272	80	51
Interest expense and amortization of deferred debt costs									(45,040)	(47,225)	(45,683)
General and administrative									(18,459)	(18,176)	(17,496)
Depreciation and amortization of deferred leasing costs									(45,861)	(45,694)	(44,417)
Acquisition related costs									0	0	(60)
Change in fair value of derivatives									(3)	70	(6)
Gain on sale of property	0	$ 0	$ 509	$ 0	0	$ 0	$ 0	$ 0	509	0	1,013
Net income (loss)									63,059	60,668	56,720
Capital investment									128,650	119,994	91,045
Total assets	1,527,489				1,422,452				1,527,489	1,422,452	1,343,025
Shopping Centers
Segment Reporting Information [Line Items]
Other revenue									0	0	0
Mixed-Use Properties
Segment Reporting Information [Line Items]
Other revenue									0	0	0
Operating Segments | Shopping Centers
Segment Reporting Information [Line Items]
Revenue									164,671	165,853	160,179
Expenses									(34,970)	(34,675)	(34,931)
Income from real estate									129,701	131,178	125,248
Interest expense and amortization of deferred debt costs									0	0	0
General and administrative									0	0	0
Depreciation and amortization of deferred leasing costs									(29,251)	(29,977)	(29,964)
Acquisition related costs											(60)
Change in fair value of derivatives									0	0	0
Gain on sale of property									509		0
Net income (loss)									100,959	101,201	95,224
Capital investment									13,485	90,896	64,044
Total assets	971,321				974,061				971,321	974,061	976,545
Operating Segments | Mixed-Use Properties
Segment Reporting Information [Line Items]
Revenue									63,233	61,352	56,840
Expenses									(21,293)	(20,917)	(18,770)
Income from real estate									41,940	40,435	38,070
Interest expense and amortization of deferred debt costs									0	0	0
General and administrative									0	0	0
Depreciation and amortization of deferred leasing costs									(16,610)	(15,717)	(14,453)
Acquisition related costs											0
Change in fair value of derivatives									0	0	0
Gain on sale of property									0		1,013
Net income (loss)									25,330	24,718	24,630
Capital investment									115,165	29,098	27,001
Total assets	537,500				438,283				537,500	438,283	358,419
Corporate
Segment Reporting Information [Line Items]
Revenue									0	0	0
Expenses									0	0	0
Income from real estate									0	0	0
Other revenue									272	80	51
Interest expense and amortization of deferred debt costs									(45,040)	(47,225)	(45,683)
General and administrative									(18,459)	(18,176)	(17,496)
Depreciation and amortization of deferred leasing costs									0	0	0
Acquisition related costs											0
Change in fair value of derivatives									(3)	70	(6)
Gain on sale of property									0		0
Net income (loss)									(63,230)	(65,251)	(63,134)
Capital investment									0	0	0
Total assets	$ 18,668				$ 10,108				$ 18,668	$ 10,108	$ 8,061

Real Estate and Accumulated D_2

Real Estate and Accumulated Depreciation (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Real Estate Properties [Line Items]
Initial Basis	$ 984,390
Cost capitalized subsequent to acquisition	963,775
Land	488,918
Buildings	1,273,275
Construction in progress	185,972	$ 91,114
Total Purchase Price	1,948,165	1,803,200	$ 1,700,813	$ 1,622,710
Accumulated Depreciation	525,518	488,166	$ 458,279	$ 425,370
Book Value	1,422,647	1,315,034
Related Debt	880,271	897,888
Development land, related debt	21,655	$ 0
Total, related debt	910,189
Shopping Centers
Real Estate Properties [Line Items]
Initial Basis	832,397
Cost capitalized subsequent to acquisition	413,662
Land	412,358
Buildings	822,249
Construction in progress	11,452
Total Purchase Price	1,246,059
Accumulated Depreciation	357,235
Book Value	888,824
Related Debt	629,111
Shopping Centers | Ashburn Village, Ashburn, VA
Real Estate Properties [Line Items]
Initial Basis	11,431
Cost capitalized subsequent to acquisition	20,391
Land	6,764
Buildings	24,957
Construction in progress	101
Total Purchase Price	31,822
Accumulated Depreciation	13,437
Book Value	18,385
Related Debt	$ 27,167
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	5,297
Construction in progress	2,211
Total Purchase Price	8,686
Accumulated Depreciation	1,991
Book Value	6,695
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	18,466
Land	22,674
Buildings	19,934
Construction in progress	19
Total Purchase Price	42,627
Accumulated Depreciation	14,814
Book Value	27,813
Related Debt	$ 38,120
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	$ 10,609
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	1,756
Land	5,735
Buildings	12,741
Construction in progress	0
Total Purchase Price	18,476
Accumulated Depreciation	4,837
Book Value	13,639
Related Debt	$ 9,601
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	4,676
Land	3,687
Buildings	5,872
Construction in progress	0
Total Purchase Price	9,559
Accumulated Depreciation	3,023
Book Value	6,536
Related Debt	$ 16,236
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	4,169
Land	9,789
Buildings	21,417
Construction in progress	0
Total Purchase Price	31,206
Accumulated Depreciation	8,606
Book Value	22,600
Related Debt	$ 12,714
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	29,223
Land	5,300
Buildings	29,226
Construction in progress	13
Total Purchase Price	34,539
Accumulated Depreciation	11,929
Book Value	22,610
Related Debt	$ 31,941
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	4,800
Land	28,401
Buildings	49,472
Construction in progress	1,139
Total Purchase Price	79,012
Accumulated Depreciation	2,324
Book Value	76,688
Related Debt	$ 38,076
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	3,811
Land	7,666
Buildings	25,045
Construction in progress	12
Total Purchase Price	32,723
Accumulated Depreciation	9,666
Book Value	23,057
Related Debt	$ 12,676
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	640
Land	6,700
Buildings	25,518
Construction in progress	0
Total Purchase Price	32,218
Accumulated Depreciation	4,802
Book Value	27,416
Related Debt	$ 16,515
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	521
Land	3,901
Buildings	8,846
Construction in progress	0
Total Purchase Price	12,747
Accumulated Depreciation	3,335
Book Value	9,412
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	14,174
Land	1,118
Buildings	18,834
Construction in progress	3
Total Purchase Price	19,955
Accumulated Depreciation	11,846
Book Value	8,109
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	353
Book Value	2,248
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	8,192
Land	5,300
Buildings	15,810
Construction in progress	0
Total Purchase Price	21,110
Accumulated Depreciation	9,582
Book Value	11,528
Related Debt	$ 22,900
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	3,192
Land	14,766
Buildings	30,174
Construction in progress	2
Total Purchase Price	44,942
Accumulated Depreciation	8,612
Book Value	36,330
Related Debt	$ 11,702
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	3,527
Land	1,856
Buildings	4,635
Construction in progress	195
Total Purchase Price	6,686
Accumulated Depreciation	3,805
Book Value	2,881
Related Debt	$ 15,345
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	4,226
Land	4,822
Buildings	11,988
Construction in progress	0
Total Purchase Price	16,810
Accumulated Depreciation	4,299
Book Value	12,511
Related Debt	$ 5,480
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	1,861
Land	4,455
Buildings	11,461
Construction in progress	0
Total Purchase Price	15,916
Accumulated Depreciation	3,848
Book Value	12,068
Related Debt	$ 6,943
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	665
Land	5,006
Buildings	9,701
Construction in progress	337
Total Purchase Price	15,044
Accumulated Depreciation	3,966
Book Value	11,078
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	1,628
Land	22,800
Buildings	55,184
Construction in progress	367
Total Purchase Price	78,351
Accumulated Depreciation	10,651
Book Value	67,700
Related Debt	$ 35,258
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	7,298
Land	1,425
Buildings	7,298
Construction in progress	0
Total Purchase Price	8,723
Accumulated Depreciation	3,988
Book Value	4,735
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	38,528
Land	6,546
Buildings	37,702
Construction in progress	825
Total Purchase Price	45,073
Accumulated Depreciation	15,011
Book Value	30,062
Related Debt	$ 31,723
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	6,262
Land	1,132
Buildings	7,548
Construction in progress	0
Total Purchase Price	8,680
Accumulated Depreciation	6,054
Book Value	2,626
Related Debt	$ 14,952
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	11,305
Land	950
Buildings	14,754
Construction in progress	1
Total Purchase Price	15,705
Accumulated Depreciation	13,062
Book Value	2,643
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	4,235
Land	26,064
Buildings	7,411
Construction in progress	3,883
Total Purchase Price	37,358
Accumulated Depreciation	1,587
Book Value	35,771
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	13,957
Land	9,260
Buildings	14,238
Construction in progress	0
Total Purchase Price	23,498
Accumulated Depreciation	5,999
Book Value	17,499
Related Debt	$ 11,295
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	15,414
Land	12,686
Buildings	15,408
Construction in progress	6
Total Purchase Price	28,100
Accumulated Depreciation	4,406
Book Value	23,694
Related Debt	$ 14,526
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	6,669
Land	5,409
Buildings	17,193
Construction in progress	0
Total Purchase Price	22,602
Accumulated Depreciation	7,672
Book Value	14,930
Related Debt	$ 9,159
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	2,106
Land	3,079
Buildings	3,990
Construction in progress	0
Total Purchase Price	7,069
Accumulated Depreciation	3,390
Book Value	3,679
Related Debt	$ 11,781
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	1,029
Land	7,751
Buildings	12,655
Construction in progress	0
Total Purchase Price	20,406
Accumulated Depreciation	3,802
Book Value	16,604
Related Debt	$ 9,728
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	1,938
Land	5,739
Buildings	14,564
Construction in progress	0
Total Purchase Price	20,303
Accumulated Depreciation	5,088
Book Value	15,215
Related Debt	$ 7,766
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	4,193
Land	703
Buildings	4,735
Construction in progress	0
Total Purchase Price	5,438
Accumulated Depreciation	3,171
Book Value	2,267
Related Debt	$ 14,086
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	918
Book Value	25,667
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	2,238
Land	43,863
Buildings	7,483
Construction in progress	2,041
Total Purchase Price	53,387
Accumulated Depreciation	6,121
Book Value	47,266
Related Debt	0
Shopping Centers | Seabreeze Plaza, Palm Harbor, FL
Real Estate Properties [Line Items]
Initial Basis	24,526
Cost capitalized subsequent to acquisition	2,315
Land	8,665
Buildings	18,176
Construction in progress	0
Total Purchase Price	26,841
Accumulated Depreciation	6,169
Book Value	20,672
Related Debt	$ 15,547
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	209
Land	1,147
Buildings	1,982
Construction in progress	0
Total Purchase Price	3,129
Accumulated Depreciation	556
Book Value	2,573
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	44,101
Land	4,913
Buildings	43,971
Construction in progress	65
Total Purchase Price	48,949
Accumulated Depreciation	29,867
Book Value	19,082
Related Debt	$ 62,630
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	512
Land	12,700
Buildings	51,066
Construction in progress	0
Total Purchase Price	63,766
Accumulated Depreciation	9,233
Book Value	54,533
Related Debt	$ 30,888
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	9,969
Land	992
Buildings	11,685
Construction in progress	0
Total Purchase Price	12,677
Accumulated Depreciation	8,343
Book Value	4,334
Related Debt	$ 10,824
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	8,218
Land	6,402
Buildings	19,629
Construction in progress	6
Total Purchase Price	26,037
Accumulated Depreciation	8,087
Book Value	17,950
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	24,825
Land	15,254
Buildings	28,465
Construction in progress	1
Total Purchase Price	43,720
Accumulated Depreciation	21,947
Book Value	21,773
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	10,998
Land	1,878
Buildings	15,848
Construction in progress	0
Total Purchase Price	17,726
Accumulated Depreciation	12,466
Book Value	5,260
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	4,417
Land	703
Buildings	6,188
Construction in progress	0
Total Purchase Price	6,891
Accumulated Depreciation	4,942
Book Value	1,949
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	25,568
Land	7,693
Buildings	25,679
Construction in progress	44
Total Purchase Price	33,416
Accumulated Depreciation	17,777
Book Value	15,639
Related Debt	$ 36,711
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	2,501
Land	7,851
Buildings	11,152
Construction in progress	0
Total Purchase Price	19,003
Accumulated Depreciation	6,995
Book Value	12,008
Related Debt	$ 13,014
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	25,265
Land	6,047
Buildings	25,262
Construction in progress	3
Total Purchase Price	31,312
Accumulated Depreciation	8,590
Book Value	22,722
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	5,387
Land	4,649
Buildings	6,837
Construction in progress	178
Total Purchase Price	11,664
Accumulated Depreciation	6,169
Book Value	5,495
Related Debt	$ 23,198
Buildings and Improvements Depreciable Lives in Years	40 years
Shopping Centers | Other Buildings / Improvements
Real Estate Properties [Line Items]
Cost capitalized subsequent to acquisition	$ 179
Buildings	179
Construction in progress	0
Total Purchase Price	179
Accumulated Depreciation	99
Book Value	80
Related Debt	0
Mixed-Use Properties
Real Estate Properties [Line Items]
Initial Basis	83,608
Cost capitalized subsequent to acquisition	435,509
Land	67,158
Buildings	451,026
Construction in progress	933
Total Purchase Price	519,117
Accumulated Depreciation	168,283
Book Value	350,834
Related Debt	$ 257,746
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	31,401
Land	3,756
Buildings	49,104
Construction in progress	0
Total Purchase Price	52,860
Accumulated Depreciation	37,712
Book Value	15,148
Related Debt	$ 27,222
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	186,038
Land	16,287
Buildings	182,504
Construction in progress	0
Total Purchase Price	198,791
Accumulated Depreciation	41,919
Book Value	156,872
Related Debt	$ 102,310
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	91,690
Land	2,242
Buildings	91,690
Construction in progress	0
Total Purchase Price	93,932
Accumulated Depreciation	7,778
Book Value	86,154
Development land, related debt	$ 69,691
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	68,712
Land	5,667
Buildings	68,524
Construction in progress	0
Total Purchase Price	74,191
Accumulated Depreciation	54,652
Book Value	19,539
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	56,734
Land	544
Buildings	58,224
Construction in progress	0
Total Purchase Price	58,768
Accumulated Depreciation	26,127
Book Value	32,641
Related Debt	$ 58,523
Buildings and Improvements Depreciable Lives in Years	50 years
Mixed-Use Properties | 7316 Wisconsin Avenue
Real Estate Properties [Line Items]
Initial Basis	$ 39,641
Cost capitalized subsequent to acquisition	934
Land	38,662
Buildings	980
Construction in progress	933
Total Purchase Price	40,575
Accumulated Depreciation	95
Book Value	40,480
Related Debt	$ 0
Buildings and Improvements Depreciable Lives in Years	2 years
Development Land
Real Estate Properties [Line Items]
Initial Basis	$ 68,385
Cost capitalized subsequent to acquisition	114,604
Land	9,402
Buildings	0
Construction in progress	173,587
Total Purchase Price	182,989
Accumulated Depreciation	0
Book Value	182,989
Development land, related debt	23,332
Development Land | Ashbrook Marketplace, Ashburn, VA
Real Estate Properties [Line Items]
Initial Basis	8,938
Cost capitalized subsequent to acquisition	2,186
Land	0
Buildings	0
Construction in progress	11,124
Total Purchase Price	11,124
Accumulated Depreciation	0
Book Value	11,124
Development land, related debt	0
Development Land | Ashland Square Phase II, Manassas, VA
Real Estate Properties [Line Items]
Initial Basis	5,292
Cost capitalized subsequent to acquisition	2,023
Land	7,028
Buildings	0
Construction in progress	287
Total Purchase Price	7,315
Accumulated Depreciation	0
Book Value	7,315
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 | North Glebe Road, Arlington, VA
Real Estate Properties [Line Items]
Initial Basis	52,067
Cost capitalized subsequent to acquisition	110,109
Land	0
Buildings	0
Construction in progress	162,176
Total Purchase Price	162,176
Accumulated Depreciation	0
Book Value	162,176
Development land, related debt	$ 23,332

Real Estate and Accumulated D_3

Real Estate and Accumulated Depreciation - Estimated Useful Lives of Assets (Detail)	12 Months Ended
	Dec. 31, 2018
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, 2018	Dec. 31, 2017
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation Disclosure [Abstract]
Real estate investments for federal income tax	$ 1,350	$ 1,320

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, 2018	Dec. 31, 2017	Dec. 31, 2016
Total real estate investments:
Balance, beginning of year	$ 1,803,200	$ 1,700,813	$ 1,622,710
Acquisitions	48,579	77,258	48,123
Improvements	98,917	42,640	35,826
Retirements	(2,531)	(17,511)	(5,846)
Balance, end of year	1,948,165	1,803,200	1,700,813
Total accumulated depreciation:
Balance, beginning of year	488,166	458,279	425,370
Depreciation expense	39,768	40,197	38,755
Retirements	(2,416)	(10,310)	(5,846)
Balance, end of year	$ 525,518	$ 488,166	$ 458,279