Stock Option Plan (Tables)

12 Months Ended

Dec. 31, 2017

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, 2017, 2016 and 2015.

SAUL CENTERS, INC. Notes to Consolidated Financial Statements (Dollars in thousands, except per share data)
Stock options issued
	Directors
Grant date		4/25/2008			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			Subtotals
Total grant		30,000			32,500			32,500			32,500			35,000			35,000			30,000			35,000			32,500			27,500			322,500
Vested		30,000			32,500			32,500			32,500			35,000			35,000			30,000			35,000			32,500			27,500			322,500
Exercised		20,000			27,500			25,000			22,500			22,500			22,500			17,500			12,500			7,500			—			177,500
Forfeited		7,500			—			2,500			2,500			—			—			—			—			—			—			12,500
Exercisable at December 31, 2017		2,500			5,000			5,000			7,500			12,500			12,500			12,500			22,500			25,000			27,500			132,500
Remaining unexercised		2,500			5,000			5,000			7,500			12,500			12,500			12,500			22,500			25,000			27,500			132,500
Exercise price		$	50.15		$	32.68		$	38.76		$	41.82		$	39.29		$	44.42		$	47.03		$	51.07		$	57.74		$	59.41
Volatility		0.237			0.344			0.369			0.358			0.348			0.333			0.173			0.166			0.166			0.173
Expected life (years)		7.0			6.0			5.0			5.0			5.0			5.0			5.0			5.0			5.0			5.0
Assumed yield		4.09		%	4.54		%	4.23		%	4.16		%	4.61		%	4.53		%	4.48		%	4.54		%	3.75		%	3.45		%
Risk-free rate		3.49		%	2.19		%	2.17		%	1.86		%	0.78		%	0.82		%	1.63		%	1.50		%	1.23		%	1.89		%
Total value at grant date		$	255		$	223		$	288		$	297		$	257		$	278		$	110		$	125		$	151		$	166		$	2,150
Expensed in previous years		255			223			288			297			257			278			110			—			—			—			1,708
Expensed in 2015		—			—			—			—			—			—			—			125			—			—			125
Expensed in 2016		—			—			—			—			—			—			—			—			151			—			151
Expensed in 2017		—			—			—			—			—			—			—			—			—			166			166
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			Subtotals									Grand Totals
Total grant		162,500			242,500			202,500			170,000			190,000			194,000			205,000			1,366,500									1,689,000
Vested		118,750			107,500			171,875			126,875			94,375			48,500			—			667,875									990,375
Exercised		96,100			91,830			116,500			41,250			20,000			3,750			—			369,430									546,930
Forfeited		43,750			135,000			30,625			1,875			3,125			1,875			—			216,250									228,750
Exercisable at December 31, 2017		22,650			15,670			55,375			85,625			74,375			44,750			—			298,445									430,945
Remaining unexercised		22,650			15,670			55,375			126,875			166,875			188,375			205,000			780,820									913,320
Exercise price		$	41.82		$	39.29		$	44.42		$	47.03		$	51.07		$	57.74		$	59.41
Volatility		0.330			0.315			0.304			0.306			0.298			0.185			0.170
Expected life (years)		8.0			8.0			8.0			7.0			7.0			7.0			7.0
Assumed yield		4.81		%	5.28		%	5.12		%	4.89		%	4.94		%	3.80		%	3.50		%
Risk-free rate		2.75		%	1.49		%	1.49		%	2.17		%	1.89		%	1.55		%	2.17		%
Gross value at grant date		$	1,366		$	1,518		$	1,401		$	1,350		$	1,585		$	1,137		$	1,324		$	9,681								$	11,831
Estimated forfeitures		368			845			212			169			142			86			92			1,914									1,914
Expensed in previous years		909			419			493			197			—			—			—			2,018									3,726
Expensed in 2015		89			157			269			296			240			—			—			1,051									1,176
Expensed in 2016		—			97			269			295			361			175			—			1,197									1,348
Expensed in 2017		—			—			158			295			361			263			205			1,282									1,448
Future expense		—			—			—			98			481			613			1,027			2,219									2,219
Weighted average term of remaining future expense		2.5			years

Summary of Option Activity

The table below summarizes the option activity for the years 2017, 2016, and 2015:

	2017				2016				2015
	Shares		Weighted Average Exercise Price		Shares		Weighted Average Exercise Price		Shares		Weighted Average Exercise Price
Outstanding at January 1	833,630		$	49.92	860,274		$	46.58	748,208		$	44.79
Granted	232,500		59.41		226,500		57.74		225,000		51.07
Exercised	(149,060	)	46.97		(246,894	)	45.59		(112,934	)	43.67
Expired/Forfeited	(3,750	)	53.73		(6,250	)	45.31		—		—
Outstanding December 31	913,320		52.80		833,630		49.92		860,274		46.58
Exercisable at December 31	430,945		48.94		375,255		46.68		435,899		45.33