Schedule III Real Estate and Accumulated Depreciation (Schedule of Changes in Rental Properties and Accumulated Depreciation) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Real Estate and Accumulated Depreciation [Line Items]
Balance	$ 250,860	$ 257,199	$ 241,128
Additions	54,759	1,504	38,198
Disposals	(121)	(7,843)	(22,220)
Impairment loss, net			93
Balance	305,498	250,860	257,199
Balance	28,877	22,929	21,548
Depreciation for the period	10,951	9,563	9,475
Depreciation on assets sold or disposed	(99)	(3,615)	(8,094)
Balance	39,729	$ 28,877	$ 22,929
Aggregate cost of land, buildings, furniture and equipment for Federal income tax purposes	$ 259,000
Minimum [Member] | Building And Improvements [Member]
Real Estate and Accumulated Depreciation [Line Items]
Useful life used for computation of depreciation	15 years
Minimum [Member] | Furniture and Equipment [Member]
Real Estate and Accumulated Depreciation [Line Items]
Useful life used for computation of depreciation	3 years
Maximum [Member] | Building And Improvements [Member]
Real Estate and Accumulated Depreciation [Line Items]
Useful life used for computation of depreciation	40 years
Maximum [Member] | Furniture and Equipment [Member]
Real Estate and Accumulated Depreciation [Line Items]
Useful life used for computation of depreciation	12 years