Consolidated Statements of Changes in Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Capital	Retained Earnings	Accumulated Other Comprehensive Income	Treasury Stock
Beginning balance (in shares) at Dec. 31, 2021		5,173,000
Beginning balance at Dec. 31, 2021	$ 252,589	$ 5,173	$ 33,415	$ 206,875	$ 7,494	$ (368)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	57,632			57,632
Dividends paid ($18.00 per common share)	(92,264)			(92,264)
Change in fair value of interest rate derivatives and other	18,092				18,092
Deferred stock unit grants	450		450
Ending balance (in shares) at Dec. 31, 2022		5,173,000
Ending balance at Dec. 31, 2022	236,499	$ 5,173	33,865	172,243	25,586	(368)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	102,413			102,413
Dividends paid ($18.00 per common share)	(92,320)			(92,320)
Change in fair value of interest rate derivatives and other	(9,385)				(9,385)
Deferred stock unit grants	$ 450		450
Ending balance (in shares) at Dec. 31, 2023	5,173,450	5,173,000
Ending balance at Dec. 31, 2023	$ 237,657	$ 5,173	34,315	182,336	16,201	(368)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	43,444			43,444
Dividends paid ($18.00 per common share)	(92,378)			(92,378)
Change in fair value of interest rate derivatives and other	(12,314)				(12,314)
Deferred stock unit grants	$ 450		450
Ending balance (in shares) at Dec. 31, 2024	5,173,450	5,173,000
Ending balance at Dec. 31, 2024	$ 176,859	$ 5,173	$ 34,765	$ 133,402	$ 3,887	$ (368)