Consolidated Statements Of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Retained Earnings	Accumulated Other Comprehensive Income
Balance, beginning of year, shares at Dec. 31, 2019		1,889
Balance, beginning of year at Dec. 31, 2019	$ 191,362	$ 0	$ 188,262	$ 3,100
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	39,420		39,420
Dividends	(31,716)		(31,716)
Shares of common stock repurchased and retired (in shares)		0
Shares of common stock repurchased and retired	(6)		(6)
Exercise of stock appreciation rights (in shares)		3
Exercise of stock appreciation rights	1		1
Share-based compensation expense	229		229
Accumulated postretirement benefit obligation adjustment	(112)			(112)
Net unrealized gain (loss) on investments	1,338			1,338
Other	(94)		(94)
Balance, end of year, shares at Dec. 31, 2020		1,892
Balance, end of year at Dec. 31, 2020	200,422	$ 0	196,096	4,326
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	67,020		67,020
Dividends	(37,553)		(37,553)
Exercise of stock appreciation rights (in shares)		3
Exercise of stock appreciation rights	(1)		(1)
Share-based compensation expense	299		299
Accumulated postretirement benefit obligation adjustment	0
Net unrealized gain (loss) on investments	(1,100)			(1,100)
Other	0
Balance, end of year, shares at Dec. 31, 2021		1,895
Balance, end of year at Dec. 31, 2021	$ 229,087	$ 0	$ 225,861	$ 3,226