Condensed Consolidated Statements of Changes in Equity - USD ($) $ 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, 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, net	161		161
Issued, net (in shares)		13
Repurchased	(16)		(16)
Restricted stock-based compensation expense	719		719
Dividends	(28,868)				(28,868)
Comprehensive income:
Net income	17,551			17,551
Unrealized net gain on cash flow hedges	3,259					3,259
Subtotal - comprehensive income	20,810			17,551		3,259
Balance at Sep. 30, 2021	151,811	$ 138	268,232	698,278	(814,281)	(556)
Balance, Shares at Sep. 30, 2021		13,784
Balance at Jun. 30, 2021	155,364	$ 138	267,951	692,934	(804,632)	(1,027)
Balance, Shares at Jun. 30, 2021		13,783
Shares of Beneficial Interest:
Issued, net	55		55
Issued, net (in shares)		1
Restricted stock-based compensation expense	226		226
Dividends	(9,649)				(9,649)
Comprehensive income:
Net income	5,344			5,344
Unrealized net gain on cash flow hedges	471					471
Subtotal - comprehensive income	5,815			5,344		471
Balance at Sep. 30, 2021	151,811	$ 138	268,232	698,278	(814,281)	(556)
Balance, Shares at Sep. 30, 2021		13,784
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, net	135		135
Issued, net (in shares)		17
Restricted stock-based compensation expense	591		591
Dividends	(29,314)				(29,314)
Comprehensive income:
Net income	15,471			15,471
Unrealized net gain on cash flow hedges	11,417					11,417
Subtotal - comprehensive income	26,888			15,471		11,417
Balance at Sep. 30, 2022	233,627	$ 138	269,241	805,030	(853,312)	12,530
Balance, Shares at Sep. 30, 2022		13,802
Balance at Jun. 30, 2022	234,646	$ 138	269,039	800,182	(843,515)	8,802
Balance, Shares at Jun. 30, 2022		13,801
Shares of Beneficial Interest:
Issued, net	42		42
Issued, net (in shares)		1
Restricted stock-based compensation expense	160		160
Dividends	(9,797)				(9,797)
Comprehensive income:
Net income	4,848			4,848
Unrealized net gain on cash flow hedges	3,728					3,728
Subtotal - comprehensive income	8,576			4,848		3,728
Balance at Sep. 30, 2022	$ 233,627	$ 138	$ 269,241	$ 805,030	$ (853,312)	$ 12,530
Balance, Shares at Sep. 30, 2022		13,802