Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	COMMON STOCK [Member]	CAPITAL SURPLUS [Member]	RETAINED EARNINGS [Member]	ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) [Member]
Balance at beginning of period at Dec. 31, 2020		$ 32,720	$ 156,574	$ 871,161	$ 7,430
Shares issued for stock options		65	1,657
Net income	$ 90,712			90,712
Dividends on common stock				(22,285)
Net cash settlement of options			(958)	(4,521)
Stock-based compensation arrangements			1,049
Net change	(2,013)				(2,013)
Balance at end of period at Jun. 30, 2021	1,131,591	32,785	158,322	935,067	5,417
Balance at beginning of period at Mar. 31, 2021		32,771	157,450	898,026	6,424
Shares issued for stock options		14	399
Net income	48,192			48,192
Dividends on common stock				(11,151)
Stock-based compensation arrangements			473
Net change	(1,007)				(1,007)
Balance at end of period at Jun. 30, 2021	1,131,591	32,785	158,322	935,067	5,417
Balance at beginning of period at Dec. 31, 2021	1,171,734	32,603	159,914	977,067	2,150
Shares issued for stock options		178	4,463
Net income	80,622			80,622
Dividends on common stock				(23,582)
Stock-based compensation arrangements			918
Net change	(48,638)				(48,638)
Balance at end of period at Jun. 30, 2022	1,185,695	32,781	165,295	1,034,107	(46,488)
Balance at beginning of period at Mar. 31, 2022		32,726	163,392	1,001,200	(29,516)
Shares issued for stock options		55	1,443
Net income	44,707			44,707
Dividends on common stock				(11,800)
Stock-based compensation arrangements			460
Net change	(16,972)				(16,972)
Balance at end of period at Jun. 30, 2022	$ 1,185,695	$ 32,781	$ 165,295	$ 1,034,107	$ (46,488)