CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Common Shares	Paid-in Capital	Accumulated Distributions in Excess of Earnings	Total Beneficial Interest	Noncontrolling Interest in Operating Partnership	Noncontrolling Interest in Partially Owned Properties	Accumulated Other Comprehensive Income (Loss)	Total
Beginning Balance at Dec. 31, 2016		$ 106,207	$ (21,480)	$ 84,727	$ 170,138	$ 3,935	$ (145)	$ 258,655
Beginning Balance (in shares) at Dec. 31, 2016	8,001
Shares issued under trustee compensation plan		59		59				59
Shares issued under trustee compensation plan (in shares)	4
Contribution of assets in exchange for the issuance of noncontrolling interest shares					14,733			14,733
Shares/units redeemed		(1,110)		(1,110)	(1,284)			(2,394)
Shares/units redeemed (in shares)	(72)
Dividends declared			(8,212)	(8,212)	(17,244)			(25,456)
Dividends reinvested - stock dividend		5,163		5,163				$ 5,163
Dividends reinvested - stock dividend (in shares)	331							331,000
Issuance of shares under optional purchase plan		3,543		3,543				$ 3,543
Issuance of shares under optional purchase plan (in shares)	216							216,000
UPREIT units converted to REIT common shares		133		133	(133)
UPREIT units converted to REIT common shares (in shares)	8
Change in fair value of interest rate swaps							80	$ 80
Distributions paid to consolidated real estate entity noncontrolling interests						(490)		(490)
Net income			6,514	6,514	13,634	(265)		19,883
Ending balance at Dec. 31, 2017		113,995	(23,179)	90,816	179,844	3,180	(65)	273,775
Ending balance (in shares) at Dec. 31, 2017	8,488
Shares issued under trustee compensation plan		57		57				57
Shares issued under trustee compensation plan (in shares)	3
Contribution of assets in exchange for the issuance of noncontrolling interest shares					7,819			7,819
Shares/units redeemed		(1,315)		(1,315)	(1,116)			(2,431)
Shares/units redeemed (in shares)	(75)
Dividends declared			(8,936)	(8,936)	(17,955)			(26,891)
Dividends reinvested - stock dividend		5,711		5,711				$ 5,711
Dividends reinvested - stock dividend (in shares)	325							325,000
Issuance of shares under optional purchase plan		4,176		4,176				$ 4,176
Issuance of shares under optional purchase plan (in shares)	226							226,000
Change in fair value of interest rate swaps							35	$ 35
Distributions paid to consolidated real estate entity noncontrolling interests						(478)		(478)
Net income			7,374	7,374	14,768	(164)		21,978
Ending balance at Dec. 31, 2018		122,624	(24,741)	97,883	183,360	2,538	(30)	$ 283,751
Ending balance (in shares) at Dec. 31, 2018	8,967							8,967,000
Shares issued under trustee compensation plan		62		62				$ 62
Shares issued under trustee compensation plan (in shares)	3
Shares/units redeemed		(891)		(891)	(1,132)			(2,023)
Shares/units redeemed (in shares)	(50)
Dividends declared			(9,681)	(9,681)	(18,626)			(28,307)
Dividends reinvested - stock dividend		6,145		6,145				$ 6,145
Dividends reinvested - stock dividend (in shares)	342							342,000
Issuance of shares under optional purchase plan		3,293		3,293				$ 3,293
Issuance of shares under optional purchase plan (in shares)	173							173,000
UPREIT units converted to REIT common shares		28		28	(28)
UPREIT units converted to REIT common shares (in shares)	1
Change in fair value of interest rate swaps							67	$ 67
Net income			5,534	5,534	10,647	(122)		16,059
Ending balance at Dec. 31, 2019		$ 131,261	$ (28,888)	$ 102,373	$ 174,221	$ 2,416	$ 37	$ 279,047
Ending balance (in shares) at Dec. 31, 2019	9,436							9,436,000