Consolidated Statements of Changes in Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock	Additional Capital	Retained Earnings	Accumulated  Other Comprehensive Income (Loss)	Treasury Stock
Beginning Balance, Shares at Dec. 31, 2020		5,173,000
Beginning Balance, value at Dec. 31, 2020	$ 203,228	$ 5,173	$ 32,965	$ 166,165	$ (707)	$ (368)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	55,181			55,181
Dividends paid	(69,160)			(69,160)
Change in fair value of interest rate derivatives and other	4,612				4,612
Deferred stock unit grants	450		450
Ending Balance, Shares at Sep. 30, 2021		5,173,000
Ending Balance, value at Sep. 30, 2021	194,311	$ 5,173	33,415	152,186	3,905	(368)
Beginning Balance, Shares at Jun. 30, 2021		5,173,000
Beginning Balance, value at Jun. 30, 2021	205,805	$ 5,173	33,415	163,845	3,740	(368)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	11,401			11,401
Dividends paid	(23,060)			(23,060)
Change in fair value of interest rate derivatives and other	165				165
Ending Balance, Shares at Sep. 30, 2021		5,173,000
Ending Balance, value at Sep. 30, 2021	$ 194,311	$ 5,173	33,415	152,186	3,905	(368)
Beginning Balance, Shares at Dec. 31, 2021	5,173,450	5,173,000
Beginning Balance, value at Dec. 31, 2021	$ 252,589	$ 5,173	33,415	206,875	7,494	(368)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	44,455			44,455
Dividends paid	(69,192)			(69,192)
Change in fair value of interest rate derivatives and other	20,044				20,044
Deferred stock unit grants	$ 450		450
Ending Balance, Shares at Sep. 30, 2022	5,173,450	5,173,000
Ending Balance, value at Sep. 30, 2022	$ 248,346	$ 5,173	33,865	182,138	27,538	(368)
Beginning Balance, Shares at Jun. 30, 2022		5,173,000
Beginning Balance, value at Jun. 30, 2022	249,916	$ 5,173	33,865	190,101	21,145	(368)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	15,109			15,109
Dividends paid	(23,072)			(23,072)
Change in fair value of interest rate derivatives and other	$ 6,393				6,393
Ending Balance, Shares at Sep. 30, 2022	5,173,450	5,173,000
Ending Balance, value at Sep. 30, 2022	$ 248,346	$ 5,173	$ 33,865	$ 182,138	$ 27,538	$ (368)