Consolidated Statement of Equity (Unaudited) - USD ($) $ in Thousands	Total	Dividend Distributions Payable	Series C Cumulative Preferred Stock Paid Dividend Paid	Series C Cumulative Preferred Stock Dividend Distributions Payable	Series D Cumulative Redeemable Preferred Stock Dividend Distributions Payable	Total Saul Centers, Inc.	Total Saul Centers, Inc. Dividend Distributions Payable	Total Saul Centers, Inc. Series C Cumulative Preferred Stock Paid Dividend Paid	Total Saul Centers, Inc. Series C Cumulative Preferred Stock Dividend Distributions Payable	Total Saul Centers, Inc. Series D Cumulative Redeemable Preferred Stock Dividend Distributions Payable	Total Saul Centers, Inc. Series E Cumulative Redeemable Preferred Stock Dividend Distributions Payable	Preferred Stock	Common Stock	Additional Paid-in Capital	Distributions in Excess of Accumulated Earnings	Distributions in Excess of Accumulated Earnings Dividend Distributions Payable	Distributions in Excess of Accumulated Earnings Series C Cumulative Preferred Stock Paid Dividend Paid	Distributions in Excess of Accumulated Earnings Series C Cumulative Preferred Stock Dividend Distributions Payable	Distributions in Excess of Accumulated Earnings Series D Cumulative Redeemable Preferred Stock Dividend Distributions Payable	Distributions in Excess of Accumulated Earnings Series E Cumulative Redeemable Preferred Stock Dividend Distributions Payable	Accumulated Other Comprehensive (Loss)	Noncontrolling Interests	Noncontrolling Interests Dividend Distributions Payable
Beginning Balance at Dec. 31, 2017	$ 393,103					$ 334,405						$ 180,000	$ 221	$ 352,590	$ (197,710)						$ (696)	$ 58,698
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of 30,000 shares of Series D Cumulative preferred stock	72,369					72,369						75,000		(2,631)
Redemption of 30,000 shares of Series C Cumulative preferred stock	(75,017)					(75,017)						(75,000)		2,311	(2,328)
Issuance of common stock:
Issuance of shares pursuant to dividend reinvestment plan	3,677					3,677							1	3,676
Issuance of shares due to exercise of employee stock options, director share grant and issuance of directors’ deferred shares	769					769							0	769
Issuance of partnership units pursuant to dividend reinvestment plan	2,017																					2,017
Net income	14,947					12,588									12,588							2,359
Change in unrealized loss on cash flow hedge	389					289															289	100
Preferred stock distributions:
Preferred stock distributions			$ (730)	$ (1,805)	$ (868)			$ (730)	$ (1,805)	$ (868)							$ (730)	$ (1,805)	$ (868)
Distributions payable, common stock and partnership units		$ (15,494)					$ (11,552)									$ (11,552)							$ (3,942)
Ending Balance at Mar. 31, 2018	393,357					334,125						180,000	222	356,715	(202,405)						(407)	59,232
Beginning Balance at Dec. 31, 2017	393,103					334,405						180,000	221	352,590	(197,710)						(696)	58,698
Issuance of common stock:
Net income	47,550
Change in unrealized loss on cash flow hedge	727
Ending Balance at Sep. 30, 2018	416,799					347,233						180,000	225	373,036	(205,872)						(156)	69,566
Beginning Balance at Mar. 31, 2018	393,357					334,125						180,000	222	356,715	(202,405)						(407)	59,232
Issuance of common stock:
Issuance of shares pursuant to dividend reinvestment plan	4,051					4,051							1	4,050
Issuance of shares due to exercise of employee stock options, director share grant and issuance of directors’ deferred shares	648					648							0	648
Issuance of partnership units pursuant to dividend reinvestment plan	10,805																					10,805
Net income	15,901					12,542									12,542							3,359
Change in unrealized loss on cash flow hedge	165					122															122	43
Preferred stock distributions:
Preferred stock distributions				(1,805)	(1,148)				(1,805)	(1,148)								(1,805)	(1,148)
Distributions payable, common stock and partnership units		(15,644)					(11,589)									(11,589)							(4,055)
Ending Balance at Jun. 30, 2018	406,330					336,946						180,000	223	361,413	(204,405)						(285)	69,384
Issuance of common stock:
Issuance of shares pursuant to dividend reinvestment plan	10,415					10,415							2	10,413
Issuance of shares due to exercise of employee stock options, director share grant and issuance of directors’ deferred shares	1,210					1,210							0	1,210
Issuance of partnership units pursuant to dividend reinvestment plan	653																					653
Net income	16,702					13,155									13,155							3,547
Change in unrealized loss on cash flow hedge	173					129															129	44
Preferred stock distributions:
Preferred stock distributions				(1,805)	(1,148)				(1,805)	(1,148)								(1,805)	(1,148)
Distributions payable, common stock and partnership units		(15,731)					(11,669)									(11,669)							(4,062)
Ending Balance at Sep. 30, 2018	416,799					347,233						180,000	225	373,036	(205,872)						(156)	69,566
Beginning Balance at Dec. 31, 2018	425,220					355,912						180,000	227	384,533	(208,593)						(255)	69,308
Issuance of common stock:
Issuance of shares pursuant to dividend reinvestment plan	6,171					6,171							1	6,170
Issuance of shares due to exercise of employee stock options, director share grant and issuance of directors’ deferred shares	420					420							1	419
Issuance of partnership units pursuant to dividend reinvestment plan	705																					705
Net income	17,077					13,447									13,447							3,630
Change in unrealized loss on cash flow hedge	(46)					(34)															(34)	(12)
Preferred stock distributions:
Preferred stock distributions				(1,805)	(1,148)				(1,805)	(1,148)								(1,805)	(1,148)
Distributions payable, common stock and partnership units		(16,263)					(12,108)									(12,108)							(4,155)
Ending Balance at Mar. 31, 2019	430,331					360,855						180,000	229	391,122	(210,207)						(289)	69,476
Beginning Balance at Dec. 31, 2018	425,220					355,912						180,000	227	384,533	(208,593)						(255)	69,308
Issuance of common stock:
Net income	49,155
Change in unrealized loss on cash flow hedge	(118)
Ending Balance at Sep. 30, 2019	545,437					475,949						290,000	231	401,395	(215,334)						(343)	69,488
Beginning Balance at Mar. 31, 2019	430,331					360,855						180,000	229	391,122	(210,207)						(289)	69,476
Issuance of common stock:
Issuance of shares pursuant to dividend reinvestment plan	5,128					5,128							1	5,127
Issuance of shares due to exercise of employee stock options, director share grant and issuance of directors’ deferred shares	2,798					2,798							0	2,798
Issuance of partnership units pursuant to dividend reinvestment plan	1,029																					1,029
Net income	16,750					13,232									13,232							3,518
Change in unrealized loss on cash flow hedge	(127)					(95)															(95)	(32)
Preferred stock distributions:
Preferred stock distributions				(1,805)	(1,148)				(1,805)	(1,148)								(1,805)	(1,148)
Distributions payable, common stock and partnership units		(16,347)					(12,181)									(12,181)							(4,166)
Ending Balance at Jun. 30, 2019	436,609					366,784						180,000	230	399,047	(212,109)						(384)	69,825
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of 30,000 shares of Series D Cumulative preferred stock	106,269					106,269						110,000		(3,731)
Issuance of common stock:
Issuance of shares pursuant to dividend reinvestment plan	5,674					5,674							1	5,673
Issuance of shares due to exercise of employee stock options, director share grant and issuance of directors’ deferred shares	406					406								406
Issuance of partnership units pursuant to dividend reinvestment plan	720																					720
Net income	15,328					12,226									12,226							3,102
Change in unrealized loss on cash flow hedge	55					41															41	14
Preferred stock distributions:
Preferred stock distributions				$ (1,805)	$ (1,148)				$ (1,805)	$ (1,148)	$ (257)							$ (1,805)	$ (1,148)	$ (257)
Distributions payable, common stock and partnership units		$ (16,414)					$ (12,241)									$ (12,241)							$ (4,173)
Ending Balance at Sep. 30, 2019	$ 545,437					$ 475,949						$ 290,000	$ 231	$ 401,395	$ (215,334)						$ (343)	$ 69,488