Schedule III: Real Estate and Accumulated Depreciation (Rollforward of Real Estate and Accumulated Deprecation) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
REAL ESTATE:
Balance at beginning of period	$ 1,071,043	$ 1,041,342	$ 1,027,691
Changes during the period	1,075,054	1,071,919	1,041,342
Less: Fully depreciated assets	(5,628)	(876)	0
Balance at end of the period	1,069,426	1,071,043	1,041,342
ACCUMULATED DEPRECIATION:
Balance at beginning of period	350,122	324,499	297,421
Additions charged to operating expenses	26,063	26,499	27,078
Subtotal of accumulated depreciation	376,185	350,998	324,499
Less: Fully depreciated assets	(5,628)	(876)	0
Balance at end of the period	370,557	350,122	324,499
Land
REAL ESTATE:
Changes during the period	(11,921)	0	0
Buildings and leasehold improvements
REAL ESTATE:
Changes during the period	5,842	31,134	5,579
Development and construction in progress
REAL ESTATE:
Changes during the period	$ 10,090	$ (557)	$ 8,072