Consolidated Statements Of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Retained Earnings	Accumulated Other Comprehensive Income
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares, outstanding		1,891
Balance, beginning of period at Dec. 31, 2023	$ 251,553	$ 0	$ 250,915	$ 638
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	13,396		13,396
Dividends paid	(1,733)		(1,733)
Repurchases of common stock (in shares)		(7)
Repurchases of common stock	(1,098)		(1,098)
Share-based compensation expense related to stock appreciation rights	168		168
Accumulated postretirement benefit obligation adjustment	0
Net unrealized gain (loss) on investments	(470)			(470)
Balance, end of period at Jun. 30, 2024	261,816	$ 0	261,648	168
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares, outstanding		1,884
Balance, beginning of period at Mar. 31, 2024	253,962	$ 0	253,616	346
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	8,871		8,871
Dividends paid	(866)		(866)
Repurchases of common stock (in shares)		0
Repurchases of common stock	(45)		(45)
Share-based compensation expense related to stock appreciation rights	72		72
Net unrealized gain (loss) on investments	(178)			(178)
Balance, end of period at Jun. 30, 2024	261,816	$ 0	261,648	168
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares, outstanding		1,884
Shares, outstanding		1,886
Balance, beginning of period at Dec. 31, 2024	251,773	$ 0	251,418	355
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	15,449		15,449
Dividends paid	(1,736)		(1,736)
Exercise of stock appreciation rights (in shares)		2
Exercise of stock appreciation rights	0		0
Share-based compensation expense related to stock appreciation rights	224		224
Accumulated postretirement benefit obligation adjustment	50			50
Net unrealized gain (loss) on investments	417			417
Balance, end of period at Jun. 30, 2025	266,177	$ 0	265,355	822
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares, outstanding		1,886
Balance, beginning of period at Mar. 31, 2025	254,412	$ 0	253,827	585
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	12,278		12,278
Dividends paid	(868)		(868)
Exercise of stock appreciation rights (in shares)		2
Exercise of stock appreciation rights	0		0
Share-based compensation expense related to stock appreciation rights	118		118
Accumulated postretirement benefit obligation adjustment	(6)			(6)
Net unrealized gain (loss) on investments	243			243
Balance, end of period at Jun. 30, 2025	$ 266,177	$ 0	$ 265,355	$ 822
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares, outstanding		1,888