Consolidated Statement of Equity (Unaudited) - USD ($) $ in Thousands	Total	Twinbrook Metro Station	Ashbrook Marketplace	Limited Partner	Limited Partner Twinbrook Metro Station	Series D Cumulative Redeemable Preferred Stock	Series E Cumulative Redeemable Preferred Stock	Total Saul Centers, Inc.	Total Saul Centers, Inc. Twinbrook Metro Station	Total Saul Centers, Inc. Series D Cumulative Redeemable Preferred Stock	Total Saul Centers, Inc. Series E Cumulative Redeemable Preferred Stock	Preferred Stock	Common Stock	Additional Paid-in Capital	Partnership Units in Escrow	Partnership Units in Escrow Twinbrook Metro Station	Distributions in Excess of Accumulated Earnings	Distributions in Excess of Accumulated Earnings Series D Cumulative Redeemable Preferred Stock	Distributions in Excess of Accumulated Earnings Series E Cumulative Redeemable Preferred Stock	Noncontrolling Interests	Noncontrolling Interests Ashbrook Marketplace	Noncontrolling Interests Limited Partner	Noncontrolling Interests Limited Partner Twinbrook Metro Station
Beginning Balance at Dec. 31, 2019	$ 443,356							$ 374,981				$ 185,000	$ 232	$ 410,926	$ 0		$ (221,177)			$ 68,375
Issuance of shares of common stock:
Issuance of shares pursuant to dividend reinvestment plan	4,081			$ 734				4,081					1	4,080								$ 734
Issuance of shares due to exercise of employee stock options and issuance of directors’ deferred shares	956							956						956
Net income	16,829							13,264									13,264			3,565
Distributions payable preferred stock:
Preferred stock distributions						$ (1,148)	$ (1,650)			$ (1,148)	$ (1,650)							$ (1,148)	$ (1,650)
Distributions payable, common stock and partnership units	(16,552)							(12,364)									(12,364)			(4,188)
Ending Balance at Mar. 31, 2020	446,606							378,120				185,000	233	415,962	0		(223,075)			68,486
Beginning Balance at Dec. 31, 2019	443,356							374,981				185,000	232	410,926	0		(221,177)			68,375
Issuance of shares of common stock:
Net income	38,640
Ending Balance at Sep. 30, 2020	431,617							367,018				185,000	234	417,504	0		(235,720)			64,599
Beginning Balance at Mar. 31, 2020	446,606							378,120				185,000	233	415,962	0		(223,075)			68,486
Issuance of shares of common stock:
Issuance of shares pursuant to dividend reinvestment plan	407							407						407
Issuance of shares due to exercise of employee stock options and issuance of directors’ deferred shares	424							424						424
Net income	10,208							8,328									8,328			1,880
Distributions payable preferred stock:
Preferred stock distributions						(1,148)	(1,650)			(1,148)	(1,650)							(1,148)	(1,650)
Distributions payable, common stock and partnership units	(16,561)							(12,373)									(12,373)			(4,188)
Ending Balance at Jun. 30, 2020	438,286							372,108				185,000	233	416,793	0		(229,918)			66,178
Issuance of shares of common stock:
Issuance of shares pursuant to dividend reinvestment plan	422							422					1	421
Issuance of shares due to exercise of employee stock options and issuance of directors’ deferred shares	290							290					0	290
Issuance of partnership units pursuant to dividend reinvestment plan	380																			380
Net income	11,603							9,367									9,367			2,236
Distributions payable preferred stock:
Preferred stock distributions						(1,148)	(1,650)			(1,148)	(1,650)							(1,148)	(1,650)
Distributions payable, common stock and partnership units	(16,566)							(12,371)									(12,371)			(4,195)
Ending Balance at Sep. 30, 2020	431,617							367,018				185,000	234	417,504	0		(235,720)			64,599
Beginning Balance at Dec. 31, 2020	427,533							364,325				185,000	235	420,625	0		(241,535)			63,208
Issuance of shares of common stock:
Issuance of shares pursuant to dividend reinvestment plan	2,840			575				2,840					1	2,839								575
Issuance of shares due to exercise of employee stock options and issuance of directors’ deferred shares	323							323						323
Stock issued during period, value, acquisitions		$ 79,300							$ 79,300							$ 79,300
Net income	12,795							10,262									10,262			2,533
Distributions payable preferred stock:
Preferred stock distributions						(1,148)	(1,650)			(1,148)	(1,650)							(1,148)	(1,650)
Distributions payable, common stock and partnership units	(16,706)							(12,488)									(12,488)			(4,218)
Ending Balance at Mar. 31, 2021	503,862							441,764				185,000	236	423,787	79,300		(246,559)			62,098
Beginning Balance at Dec. 31, 2020	427,533							364,325				185,000	235	420,625	0		(241,535)			63,208
Issuance of shares of common stock:
Net income	45,799
Ending Balance at Sep. 30, 2021	529,607							442,765				185,000	237	430,537	79,300		(252,309)			86,842
Beginning Balance at Mar. 31, 2021	503,862							441,764				185,000	236	423,787	79,300		(246,559)			62,098
Issuance of shares of common stock:
Issuance of shares pursuant to dividend reinvestment plan	2,855			$ 585				2,855						2,855								$ 585
Issuance of shares due to exercise of employee stock options and issuance of directors’ deferred shares	705							705						705
Stock issued during period, value, acquisitions			$ 4,320		$ 21,500																$ 4,320		$ 21,500
Net income	16,119							12,746									12,746			3,373
Distributions payable preferred stock:
Preferred stock distributions						(1,149)	(1,650)			(1,149)	(1,650)							(1,149)	(1,650)
Distributions payable, common stock and partnership units	(17,694)							(13,000)									(13,000)			(4,694)
Ending Balance at Jun. 30, 2021	529,453							442,271				185,000	236	427,347	79,300		(249,612)			87,182
Issuance of shares of common stock:
Issuance of shares pursuant to dividend reinvestment plan	2,897							2,897					1	2,896
Issuance of shares due to exercise of employee stock options and issuance of directors’ deferred shares	294							294					0	294
Issuance of partnership units pursuant to dividend reinvestment plan	615																			615
Net income	16,885							13,138									13,138			3,747
Distributions payable preferred stock:
Preferred stock distributions						$ (1,148)	$ (1,650)			$ (1,148)	$ (1,650)							$ (1,148)	$ (1,650)
Distributions payable, common stock and partnership units	(17,739)							(13,037)									(13,037)			(4,702)
Ending Balance at Sep. 30, 2021	$ 529,607							$ 442,765				$ 185,000	$ 237	$ 430,537	$ 79,300		$ (252,309)			$ 86,842