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, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Total revenue	$ 58,284	$ 56,760	$ 53,220	$ 56,943	$ 56,582	$ 57,052	$ 58,141	$ 59,750	$ 225,207	$ 231,525	$ 227,219
Net Income	11,676	11,603	10,208	16,829	15,041	15,328	16,750	17,077
Net income attributable to Saul Centers, Inc.	9,423	9,367	8,328	13,264	12,818	12,226	13,232	13,447	40,382	51,723	50,554
Net income available to common stockholders	$ 6,623	$ 6,569	$ 5,530	$ 10,466	$ 6,464	$ 9,016	$ 10,279	$ 10,494	$ 29,188	$ 36,253	$ 35,964
Net income available to common stockholders per diluted share (in usd per share)	$ 0.28	$ 0.28	$ 0.24	$ 0.45					$ 1.25	$ 1.57	$ 1.60
Net income available to common stockholders per basic and diluted share (in usd per share)					$ 0.27	$ 0.39	$ 0.45	$ 0.46