CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (UNAUDITED) - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income	Retained Earnings	Treasury Stock
Balance (in shares) at Dec. 31, 2020		11,822
Balance at Dec. 31, 2020	$ 157,246	$ 12	$ 7,842	$ 41	$ 154,351	$ (5,000)
Net income	41,063				41,063
Share-based compensation (in shares)		13
Share-based compensation	2,198		2,198
Options exercised by executives and directors (in shares)		11
Options exercised by executives and directors	481		481
Net shares repurchased for taxes (in shares)		(7)
Net shares repurchased for taxes	(1,807)		(1,807)
Treasury stock from stock repurchases	(7,500)					(7,500)
Other comprehensive income	62			62
Cash dividends declared to stockholders	(16,852)				(16,852)
Balance (in shares) at Mar. 31, 2021		11,839
Balance at Mar. 31, 2021	174,891	$ 12	8,714	103	178,562	(12,500)
Balance (in shares) at Dec. 31, 2020		11,822
Balance at Dec. 31, 2020	157,246	$ 12	7,842	41	154,351	(5,000)
Net income	$ 88,026
Net shares repurchased for taxes (in shares)	(7)
Other comprehensive income	$ 34
Balance (in shares) at Jun. 30, 2021		11,738
Balance at Jun. 30, 2021	194,689	$ 12	10,606	75	185,343	(1,347)
Balance (in shares) at Mar. 31, 2021		11,839
Balance at Mar. 31, 2021	174,891	$ 12	8,714	103	178,562	(12,500)
Net income	46,963				46,963
Share-based compensation (in shares)		10
Share-based compensation	1,839		1,697		142
Options exercised by executives and directors (in shares)		3
Options exercised by executives and directors	221		221
Net shares repurchased for taxes	(26)		(26)			0
Treasury stock from stock repurchases	$ (12,230)					(12,230)
Treasury stock retire from stock repurchases (in shares)	(114)
Treasury stock retired from stock repurchases	$ 0				(23,383)	23,383
Other comprehensive income	(28)			(28)		0
Cash dividends declared to stockholders	(16,941)				(16,941)
Balance (in shares) at Jun. 30, 2021		11,738
Balance at Jun. 30, 2021	194,689	$ 12	10,606	75	185,343	(1,347)
Balance (in shares) at Dec. 31, 2021		11,594
Balance at Dec. 31, 2021	202,474	$ 12	12,018	111	190,333	0
Net income	41,781				41,781
Share-based compensation (in shares)		18
Share-based compensation	2,275		2,275
Net shares repurchased for taxes (in shares)		(8)
Net shares repurchased for taxes	(1,459)		(1,459)
Treasury stock from stock repurchases	(10,000)					(10,000)
Treasury stock retire from stock repurchases (in shares)		(51)
Treasury stock retired from stock repurchases	0				(10,000)	10,000
Other comprehensive income	16			16
Cash dividends declared to stockholders	(19,063)				(19,063)
Balance (in shares) at Mar. 31, 2022		11,553
Balance at Mar. 31, 2022	216,024	$ 12	12,834	127	203,051	0
Balance (in shares) at Dec. 31, 2021		11,594
Balance at Dec. 31, 2021	202,474	$ 12	12,018	111	190,333	0
Net income	$ 80,894
Net shares repurchased for taxes (in shares)	(8)
Other comprehensive income	$ 156
Balance (in shares) at Jun. 30, 2022		11,019
Balance at Jun. 30, 2022	129,476	$ 11	0	268	129,197	0
Balance (in shares) at Mar. 31, 2022		11,553
Balance at Mar. 31, 2022	216,024	$ 12	12,834	127	203,051	0
Net income	39,113				39,113
Share-based compensation (in shares)		1
Share-based compensation	2,865		2,865
Net shares repurchased for taxes	(20)		(20)			0
Treasury stock from stock repurchases	$ (90,038)					(90,038)
Treasury stock retire from stock repurchases (in shares)	(535)
Treasury stock retired from stock repurchases	$ (1)				(90,038)	90,038
Stock repurchases, not yet settled	(20,010)		(15,679)		(4,331)
Other comprehensive income	141			141
Cash dividends declared to stockholders	(18,598)				(18,598)
Balance (in shares) at Jun. 30, 2022		11,019
Balance at Jun. 30, 2022	$ 129,476	$ 11	$ 0	$ 268	$ 129,197	$ 0