CONSOLIDATED STATEMENTS OF COMMON SHAREHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Paid-in Capital	Treasury Stock	Retained Earnings	Accumulated Other Comprehensive Loss
Balance at Dec. 31, 2019	$ 2,039,094	$ 541	$ 1,508,970	$ (96,015)	$ 635,246	$ (9,648)
Shares, Balance at Dec. 31, 2019		53,999		3,547
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Net Income	155,215	$ 0	0	$ 0	155,215	0
Foreign currency translation adjustment	87	0	0	0	0	87
Reclassification of net income (loss) on derivative instruments	(452)	0	0	0	0	(452)
Postretirement medical liability adjustment, net of tax	1,840	0	0	0	0	1,840
Stock based compensation, value	$ 1,359	$ 0	4,100	$ (2,741)	0	0
Stock based compensation, shares		146		35
Treasury Stock, Shares, Acquired	(24)
Issuance of shares, value	$ 1,398	$ 0	717		0	0
Issuance of shares, shares		0
Issuance of shares, value, treasury stock reissued				$ 681
Dividends on common stock	(120,350)	$ 0	0	0	(120,350)	0
Balance at Dec. 31, 2020	$ 2,079,095	$ 541	1,513,787	$ (98,075)	670,111	(7,269)
Shares, Balance at Dec. 31, 2020		54,145		3,558
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Dividends per share	$ 2.40
Net Income	$ 186,840	$ 0	0	$ 0	186,840	0
Foreign currency translation adjustment	(57)	0	0	0	0	(57)
Reclassification of net income (loss) on derivative instruments	(452)	0	0	0	0	(452)
Postretirement medical liability adjustment, net of tax	(436)	0	0	0	0	(436)
Stock based compensation, value	$ 4,328	$ 1	5,298	$ (971)	0	0
Stock based compensation, shares		93		17
Treasury Stock, Shares, Acquired	(29)
Issuance of shares, value	$ 197,974	$ 34	197,142		0	0
Issuance of shares, shares		3,368
Issuance of shares, value, treasury stock reissued				$ 798
Dividends on common stock	(128,483)	$ 0	0	0	(128,483)	0
Balance at Dec. 31, 2021	$ 2,339,713	$ 576	1,716,227	$ (98,248)	728,468	(7,310)
Shares, Balance at Dec. 31, 2021		57,606		3,546
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Dividends per share	$ 2.48
Net Income	$ 183,008	$ 0	0	$ 0	183,008	0
Foreign currency translation adjustment	(8)	0	0	0	0	(8)
Reclassification of net income (loss) on derivative instruments	(452)	0	0	0	0	(452)
Postretirement medical liability adjustment, net of tax	(982)	0	0	0	0	982
Stock based compensation, value	$ 6,480	$ 0	7,391	$ (911)	0	0
Stock based compensation, shares		87		16
Treasury Stock, Shares, Acquired	(28)
Issuance of shares, value	$ 276,582	$ 57	275,758		0	0
Issuance of shares, shares		5,585
Issuance of shares, value, treasury stock reissued				$ 767
Dividends on common stock	(140,062)	$ 0	0	0	(140,062)	0
Balance at Dec. 31, 2022	$ 2,665,183	$ 633	$ 1,999,376	$ (98,392)	$ 771,414	$ (7,848)
Shares, Balance at Dec. 31, 2022		63,278		3,534
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Dividends per share	$ 2.52