Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	COMMON STOCK [Member]	CAPITAL SURPLUS [Member]	RETAINED EARNINGS [Member]	ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)
Balance at beginning of period, Shares at Dec. 31, 2020		32,719,852
Balance at beginning of period at Dec. 31, 2020		$ 32,720	$ 156,574	$ 871,161	$ 7,430
Shares issued for stock options, Shares		95,562
Shares issued for stock options, Value		$ 95	2,165
Net income	$ 167,630			167,630
Net change					(5,280)
Dividends on common stock				(45,752)
Net cash settlement of options			(958)	(4,521)
Stock-based compensation arrangements			2,133
Shares acquired and canceled, Shares		(212,296)
Shares acquired and canceled, Value		$ (212)		(11,451)
Balance at end of period, Shares at Dec. 31, 2021	32,603,118	32,603,118
Balance at end of period at Dec. 31, 2021	$ 1,171,734	$ 32,603	159,914	977,067	2,150
Shares issued for stock options, Shares		272,442
Shares issued for stock options, Value		$ 273	7,376
Net income	$ 193,100			193,100
Net change					(73,713)
Dividends on common stock				(49,875)
Stock-based compensation arrangements			1,941
Balance at end of period, Shares at Dec. 31, 2022	32,875,560	32,875,560
Balance at end of period at Dec. 31, 2022	$ 1,250,836	$ 32,876	169,231	1,120,292	(71,563)
Shares issued for stock options, Shares		78,160
Shares issued for stock options, Value		$ 78	2,465
Net income	$ 212,465			212,465
Net change					21,521
Dividends on common stock				(54,653)
Stock-based compensation arrangements			2,999
Shares acquired and canceled, Shares		(20,702)
Shares acquired and canceled, Value		$ (21)		(1,799)
Balance at end of period, Shares at Dec. 31, 2023	32,933,018	32,933,018
Balance at end of period at Dec. 31, 2023	$ 1,433,891	$ 32,933	$ 174,695	$ 1,276,305	$ (50,042)