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, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Revenue	$ 56,675	$ 56,237	$ 55,907	$ 58,466	$ 54,201	$ 53,233	$ 52,710	$ 56,926	$ 227,285	$ 217,070	$ 209,077
Operating income before loss on early extinguishment of debt, gain on casualty settlement, and noncontrolling interests	14,416	14,386	14,422	17,374	13,360	12,722	13,250	16,381	60,598	55,713	52,930
Gains on sales of properties	0	0	0	0	1,013	0	0	0	0	1,013	11
Net income attributable to Saul Centers, Inc.	11,560	11,483	11,510	13,704	11,465	10,239	10,627	12,948	48,257	45,279	42,468
Net income available to common stockholders	$ 8,466	$ 8,390	$ 8,416	$ 10,610	$ 8,371	$ 7,146	$ 7,533	$ 9,854	$ 35,882	$ 32,904	$ 30,093
Net income available to common stockholders per diluted share (in usd per share)	$ 0.38	$ 0.38	$ 0.38	$ 0.49	$ 0.38	$ 0.33	$ 0.35	$ 0.46	$ 1.63	$ 1.52	$ 1.42