CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY Statement - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Treasury Stock, Common	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss [Member]
Balance, shares at Dec. 31, 2021		57,606	3,546
Balance, beginning of period at Dec. 31, 2021	$ 2,339,713	$ 576	$ (98,248)	$ 1,716,227	$ 728,468	$ (7,310)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	116,264	0	0	0	116,264	0
Foreign currency translation adjustment	5	0	0	0	0	(5)
Reclassification of net losses on derivative instruments	339	0	0	0	0	339
Postretirement medical liability adjustment	(474)	$ 0	$ 0	0	0	(474)
Stock based compensation, shares		87	16
Stock based compensation, value	5,146	$ 1	$ (911)	6,056	0	0
Issuance of shares		3,625
Issuance of shares, treasury stock			(21)
Issuance of shares, value	179,326	$ 36	$ 581	178,709	0	0
Dividends on common stock	$ (102,980)	$ 0	$ 0	0	(102,980)	0
Dividends per share	$ 1.89
Balance, shares at Sep. 30, 2022		61,318	3,541
Balance, end of period at Sep. 30, 2022	$ 2,537,329	$ 613	$ (98,578)	1,900,992	741,752	(7,450)
Balance, shares at Jun. 30, 2022		59,697	3,548
Balance, beginning of period at Jun. 30, 2022	2,464,520	$ 597	$ (98,765)	1,820,531	749,558	(7,401)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	27,368	0	0	0	27,368	0
Foreign currency translation adjustment	4	0	0	0	0	4
Reclassification of net losses on derivative instruments	113	0	0	0	0	113
Postretirement medical liability adjustment	(158)	$ 0	$ 0	0	0	(158)
Stock based compensation, shares		0	0
Stock based compensation, value	2,080	$ 0	$ 0	2,080	0	0
Issuance of shares		1,621
Issuance of shares, treasury stock			(7)
Stock Issued During Period, Value, Treasury Stock Reissued			$ 187
Issuance of shares, value	78,584	$ 16		78,381	0	0
Dividends on common stock	$ (35,174)	$ 0	$ 0	0	(35,174)	0
Dividends per share	$ 0.630
Balance, shares at Sep. 30, 2022		61,318	3,541
Balance, end of period at Sep. 30, 2022	$ 2,537,329	$ 613	$ (98,578)	1,900,992	741,752	(7,450)
Balance, shares at Dec. 31, 2022		63,278	3,534
Balance, beginning of period at Dec. 31, 2022	2,665,183	$ 633	$ (98,392)	1,999,376	771,414	(7,848)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	110,989	0	0	0	110,989	0
Foreign currency translation adjustment	10	0	0	0	0	10
Reclassification of net losses on derivative instruments	339	0	0	0	0	339
Postretirement medical liability adjustment	(502)	$ 0	$ 0	0	0	(502)
Stock based compensation, shares		51	0
Stock based compensation, value	4,911	$ 0	$ 0	4,911	0	0
Issuance of shares		1,433
Issuance of shares, treasury stock			(14)
Issuance of shares, value	74,552	$ 15	$ 270	74,267	0	0
Dividends on common stock	$ (115,048)	$ 0	$ 0	0	(115,048)	0
Dividends per share	$ 1.920
Balance, shares at Sep. 30, 2023		64,762	3,520
Balance, end of period at Sep. 30, 2023	$ 2,740,414	$ 648	$ (98,122)	2,078,554	767,355	(8,021)
Balance, shares at Jun. 30, 2023		63,518	3,527
Balance, beginning of period at Jun. 30, 2023	2,686,724	$ 635	$ (98,302)	2,015,367	776,983	(7,959)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	29,335	0	0	0	29,335	0
Foreign currency translation adjustment	7	0	0	0	0	7
Reclassification of net losses on derivative instruments	113	0	0	0	0	113
Postretirement medical liability adjustment	(168)	$ 0	$ 0	0	0	(168)
Stock based compensation, shares		0	0
Stock based compensation, value	239	$ 0	$ 0	239	0	0
Issuance of shares		1,244
Issuance of shares, treasury stock			(7)
Stock Issued During Period, Value, Treasury Stock Reissued			$ 180
Issuance of shares, value	63,141	$ 13		62,948	0	0
Dividends on common stock	$ (38,963)	$ 0	$ 0	0	(38,963)	0
Dividends per share	$ 0.640
Balance, shares at Sep. 30, 2023		64,762	3,520
Balance, end of period at Sep. 30, 2023	$ 2,740,414	$ 648	$ (98,122)	$ 2,078,554	$ 767,355	$ (8,021)