Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Deferred Compensation Trust [Member]	Retained Earnings [Member]
Beginning Balance at Dec. 31, 2020	$ 961,288	$ 26	$ 267,666	$ (2,944)	$ 696,540
Beginning Balance, Shares at Dec. 31, 2020		26,236,570
Stock compensation, including options and long-term incentives	1,711		1,711
Exercise of stock options less shares withheld for taxes	3,678		3,678
Exercise of stock options less shares withheld for taxes, Shares		46,741
Shares issued for long-term incentive awards, net of shares withheld for taxes, Shares		50,381
Shares issued for long-term incentive awards, net of shares withheld for taxes	(6,350)		6,350
Purchase of shares by Deferred Compensation Trust			(742)	742
Sale of shares by Deferred Compensation Trust			(17)	17
Net income	37,291				37,291
Ending Balance at Mar. 31, 2021	997,618	$ 26	267,430	(3,669)	733,831
Ending Balance, Shares at Mar. 31, 2021		26,333,692
Beginning Balance at Dec. 31, 2020	961,288	$ 26	267,666	(2,944)	696,540
Beginning Balance, Shares at Dec. 31, 2020		26,236,570
Net income	99,765
Ending Balance at Jun. 30, 2021	1,063,158	$ 26	270,608	(3,781)	796,305
Ending Balance, Shares at Jun. 30, 2021		26,335,096
Beginning Balance at Mar. 31, 2021	997,618	$ 26	267,430	(3,669)	733,831
Beginning Balance, Shares at Mar. 31, 2021		26,333,692
Stock compensation, including options and long-term incentives	1,810		1,810
Director deferred share activity	1,256		1,256
Director deferred share activity , Shares		1,404
Purchase of shares by Deferred Compensation Trust			(112)	112
Net income	62,474				62,474
Ending Balance at Jun. 30, 2021	1,063,158	$ 26	270,608	(3,781)	796,305
Ending Balance, Shares at Jun. 30, 2021		26,335,096
Beginning Balance at Dec. 31, 2021	1,220,333	$ 26	274,633	(4,101)	949,775
Beginning Balance, Shares at Dec. 31, 2021		26,336,589
Stock compensation, including options and long-term incentives	2,056		2,056
Exercise of stock options less shares withheld for taxes	907		907
Exercise of stock options less shares withheld for taxes, Shares		10,992
Shares issued for long-term incentive awards, net of shares withheld for taxes, Shares		60,821
Shares issued for long-term incentive awards, net of shares withheld for taxes	(11,230)		11,230
Purchase of shares by Deferred Compensation Trust			(2,445)	2,445
Sale of shares by Deferred Compensation Trust			(1,066)	1,066
Net income	79,424				79,424
Ending Balance at Mar. 31, 2022	1,291,490	$ 26	267,745	(5,480)	1,029,199
Ending Balance, Shares at Mar. 31, 2022		26,408,402
Beginning Balance at Dec. 31, 2021	1,220,333	$ 26	274,633	(4,101)	949,775
Beginning Balance, Shares at Dec. 31, 2021		26,336,589
Net income	188,669
Ending Balance at Jun. 30, 2022	1,403,762	$ 26	271,395	(6,103)	1,138,444
Ending Balance, Shares at Jun. 30, 2022		26,411,736
Beginning Balance at Mar. 31, 2022	1,291,490	$ 26	267,745	(5,480)	1,029,199
Beginning Balance, Shares at Mar. 31, 2022		26,408,402
Stock compensation, including options and long-term incentives	1,756		1,756
Director deferred share activity	1,170		1,170
Director deferred share activity , Shares		2,327
Exercise of stock options less shares withheld for taxes	101		101
Exercise of stock options less shares withheld for taxes, Shares		1,007
Purchase of shares by Deferred Compensation Trust			(631)	631
Sale of shares by Deferred Compensation Trust			(8)	8
Net income	109,245				109,245
Ending Balance at Jun. 30, 2022	$ 1,403,762	$ 26	$ 271,395	$ (6,103)	$ 1,138,444
Ending Balance, Shares at Jun. 30, 2022		26,411,736