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, 2017	$ 8,488	$ 113,995	$ (23,179)	$ 90,816	$ 179,844	$ 3,180	$ (65)	$ 273,775
Contribution of assets in exchange for the issuance of noncontrolling interest shares					1,546			1,546
Shares/units redeemed		(614)		(614)	(316)			(930)
Shares/units redeemed (in shares)	(35,000)
Dividends declared			(2,190)	(2,190)	(4,473)			(6,663)
Dividends reinvested - stock dividend		1,373		1,373				1,373
Dividends reinvested - stock dividend (in shares)	79,000
Issuance of shares under optional purchase plan		1,411		1,411				1,411
Issuance of shares under optional purchase plan (in shares)	76,000
Change in fair value of interest rate swaps							14	14
Net income			1,741	1,741	3,536	(19)		5,258
Ending balance at Mar. 31, 2018		116,165	(23,628)	92,537	180,137	3,161	(51)	275,784
Ending balance (in shares) at Mar. 31, 2018	8,608,000
Beginning Balance at Dec. 31, 2017	$ 8,488	113,995	(23,179)	90,816	179,844	3,180	(65)	$ 273,775
Dividends reinvested - stock dividend (in shares)								243,000
Change in fair value of interest rate swaps								$ 32
Net income								17,321
Ending balance at Sep. 30, 2018		120,289	(24,037)	96,252	179,195	2,576	(33)	277,990
Ending balance (in shares) at Sep. 30, 2018	8,837,000
Beginning Balance at Mar. 31, 2018		116,165	(23,628)	92,537	180,137	3,161	(51)	275,784
Beginning Balance (in shares) at Mar. 31, 2018	8,608,000
Shares/units redeemed		(244)		(244)	(489)			(733)
Shares/units redeemed (in shares)	(14,000)
Dividends declared			(2,217)	(2,217)	(4,465)			(6,682)
Dividends reinvested - stock dividend		1,425		1,425				1,425
Dividends reinvested - stock dividend (in shares)	81,000
Issuance of shares under optional purchase plan		747		747				747
Issuance of shares under optional purchase plan (in shares)	40,000
Change in fair value of interest rate swaps							10	10
Net income			1,677	1,677	3,376	(74)		4,979
Ending balance at Jun. 30, 2018		118,093	(24,168)	93,925	178,559	3,087	(41)	275,530
Ending balance (in shares) at Jun. 30, 2018	8,715,000
Shares issued under trustee compensation plan		57		57				57
Shares issued under trustee compensation plan (in shares)	3,000
Contribution of assets in exchange for the issuance of noncontrolling interest shares					630			630
Shares/units redeemed		(241)		(241)	(263)			(504)
Shares/units redeemed (in shares)	(14,000)
Dividends declared			(2,248)	(2,248)	(4,470)			(6,718)
Dividends reinvested - stock dividend		1,458		1,458				1,458
Dividends reinvested - stock dividend (in shares)	83,000
Issuance of shares under optional purchase plan		922		922				922
Issuance of shares under optional purchase plan (in shares)	50,000
Change in fair value of interest rate swaps							8	8
Distributions paid to consolidated real estate entity noncontrolling interests						(477)		(477)
Net income			2,379	2,379	4,739	(34)		7,084
Ending balance at Sep. 30, 2018		120,289	(24,037)	96,252	179,195	2,576	(33)	277,990
Ending balance (in shares) at Sep. 30, 2018	8,837,000
Beginning Balance at Dec. 31, 2018		122,624	(24,741)	97,883	183,360	2,538	(30)	$ 283,751
Beginning Balance (in shares) at Dec. 31, 2018	8,967,000							8,967,000
Shares/units redeemed		(197)		(197)	(629)			$ (826)
Shares/units redeemed (in shares)	(11,000)
Dividends declared			(2,374)	(2,374)	(4,661)			(7,035)
Dividends reinvested - stock dividend		1,479		1,479				1,479
Dividends reinvested - stock dividend (in shares)	82,000
Issuance of shares under optional purchase plan		929		929				929
Issuance of shares under optional purchase plan (in shares)	49,000
Change in fair value of interest rate swaps							4	4
Net income			1,288	1,288	2,532	(30)		3,790
Ending balance at Mar. 31, 2019		124,835	(25,827)	99,008	180,602	2,508	(26)	282,092
Ending balance (in shares) at Mar. 31, 2019	9,087,000
Beginning Balance at Dec. 31, 2018		122,624	(24,741)	97,883	183,360	2,538	(30)	$ 283,751
Beginning Balance (in shares) at Dec. 31, 2018	8,967,000							8,967,000
Dividends reinvested - stock dividend (in shares)								255,000
Change in fair value of interest rate swaps								$ 14
Net income								12,081
Ending balance at Sep. 30, 2019		129,123	(27,809)	101,314	176,413	2,437	(16)	$ 280,148
Ending balance (in shares) at Sep. 30, 2019	9,320,000							9,320,000
Beginning Balance at Mar. 31, 2019		124,835	(25,827)	99,008	180,602	2,508	(26)	$ 282,092
Beginning Balance (in shares) at Mar. 31, 2019	9,087,000
Shares/units redeemed		(154)		(154)	(272)			(426)
Shares/units redeemed (in shares)	(9,000)
Dividends declared			(2,407)	(2,407)	(4,657)			(7,064)
Dividends reinvested - stock dividend		1,554		1,554				1,554
Dividends reinvested - stock dividend (in shares)	86,000
Issuance of shares under optional purchase plan		795		795				795
Issuance of shares under optional purchase plan (in shares)	42,000
Change in fair value of interest rate swaps							4	4
Net income			1,647	1,647	3,190	(16)		4,821
Ending balance at Jun. 30, 2019		127,030	(26,587)	100,443	178,863	2,492	(22)	281,776
Ending balance (in shares) at Jun. 30, 2019	9,206,000
Shares issued under trustee compensation plan		62		62				62
Shares issued under trustee compensation plan (in shares)	3,000
Shares/units redeemed		(242)		(242)	(79)			(321)
Shares/units redeemed (in shares)	(13,000)
Dividends declared			(2,435)	(2,435)	(4,655)			(7,090)
Dividends reinvested - stock dividend		1,558		1,558				1,558
Dividends reinvested - stock dividend (in shares)	87,000
Issuance of shares under optional purchase plan		687		687				687
Issuance of shares under optional purchase plan (in shares)	36,000
UPREIT units converted to REIT common shares		28		28	(28)
UPREIT units converted to REIT common shares (in shares)	1,000
Change in fair value of interest rate swaps							6	6
Net income			1,213	1,213	2,312	(55)		3,470
Ending balance at Sep. 30, 2019		$ 129,123	$ (27,809)	$ 101,314	$ 176,413	$ 2,437	$ (16)	$ 280,148
Ending balance (in shares) at Sep. 30, 2019	9,320,000							9,320,000