CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common stock	Capital in excess of par value	Cumulative net income	Cumulative dividends	Accumulated other comprehensive income/(loss)
Balance at Dec. 31, 2019	$ 181,734	$ 138	$ 266,723	$ 661,280	$ (747,417)	$ 1,010
Balance, Shares at Dec. 31, 2019		13,757
Shares of Beneficial Interest:
Issued	(32)		(32)
Issued (in shares)		16
Repurchased	(235)		(235)
Repurchased (in shares)		(2)
Restricted stock-based compensation expense	912		912
Dividends	(37,996)				(37,996)
Comprehensive income:
Net income	19,447			19,447
Unrealized net gain on cash flow hedges	(4,825)					(4,825)
Subtotal - comprehensive income	14,622			19,447		(4,825)
Balance at Dec. 31, 2020	159,005	$ 138	267,368	680,727	(785,413)	(3,815)
Balance, Shares at Dec. 31, 2020		13,771
Shares of Beneficial Interest:
Issued	216		216
Issued (in shares)		14
Repurchased	(16)		(16)
Restricted stock-based compensation expense	947		947
Dividends	(38,585)				(38,585)
Comprehensive income:
Net income	109,166			109,166
Net income/(loss) applicable to noncontrolling interest	(334)			(334)
Unrealized net gain on cash flow hedges	4,928					4,928
Subtotal - comprehensive income	113,760			108,832		4,928
Balance at Dec. 31, 2021	235,327	$ 138	268,515	789,559	(823,998)	1,113
Balance, Shares at Dec. 31, 2021		13,785
Shares of Beneficial Interest:
Issued	177		177
Issued (in shares)		18
Restricted stock-based compensation expense	780		780
Dividends	(39,183)				(39,183)
Comprehensive income:
Net income	21,102			21,102
Unrealized net gain on cash flow hedges	10,898					10,898
Subtotal - comprehensive income	32,000			21,102		10,898
Balance at Dec. 31, 2022	$ 229,101	$ 138	$ 269,472	$ 810,661	$ (863,181)	$ 12,011
Balance, Shares at Dec. 31, 2022		13,803