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, 2022		5,173,000
Beginning balance, value at Dec. 31, 2022	$ 236,499	$ 5,173	$ 33,865	$ 172,243	$ 25,586	$ (368)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	75,373			75,373
Dividends paid	(46,144)			(46,144)
Change in fair value of interest rate derivatives and other	(534)				(534)
Deferred stock unit grants	450		450
Ending balance, (in shares) at Jun. 30, 2023		5,173,000
Ending balance, value at Jun. 30, 2023	265,644	$ 5,173	34,315	201,472	25,052	(368)
Beginning balance, (in shares) at Mar. 31, 2023		5,173,000
Beginning balance, value at Mar. 31, 2023	221,009	$ 5,173	33,865	160,397	21,942	(368)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	64,147			64,147
Dividends paid	(23,072)			(23,072)
Change in fair value of interest rate derivatives and other	3,110				3,110
Deferred stock unit grants	450		450
Ending balance, (in shares) at Jun. 30, 2023		5,173,000
Ending balance, value at Jun. 30, 2023	$ 265,644	$ 5,173	34,315	201,472	25,052	(368)
Beginning balance, (in shares) at Dec. 31, 2023	5,173,450	5,173,000
Beginning balance, value at Dec. 31, 2023	$ 237,657	$ 5,173	34,315	182,336	16,201	(368)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	24,489			24,489
Dividends paid	(46,176)			(46,176)
Change in fair value of interest rate derivatives and other	(3,900)				(3,900)
Deferred stock unit grants	$ 450		450
Ending balance, (in shares) at Jun. 30, 2024	5,173,450	5,173,000
Ending balance, value at Jun. 30, 2024	$ 212,520	$ 5,173	34,765	160,649	12,301	(368)
Beginning balance, (in shares) at Mar. 31, 2024		5,173,000
Beginning balance, value at Mar. 31, 2024	230,138	$ 5,173	34,315	175,357	15,661	(368)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	8,380			8,380
Dividends paid	(23,088)			(23,088)
Change in fair value of interest rate derivatives and other	(3,360)				(3,360)
Deferred stock unit grants	$ 450		450
Ending balance, (in shares) at Jun. 30, 2024	5,173,450	5,173,000
Ending balance, value at Jun. 30, 2024	$ 212,520	$ 5,173	$ 34,765	$ 160,649	$ 12,301	$ (368)