Condensed Consolidated Statements Of Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock Outstanding [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss [Member]	Treasury Stock [Member]
Balance (in shares) at Jun. 30, 2021		27,531,000
Balance at Jun. 30, 2021	$ 843,147	$ 128,617	$ 1,482,220	$ (8,253)	$ (759,437)
Net income	30,655		30,655
Net pension and postretirement benefit gains, net of tax effect	42			42
Cash dividends - common stock	(20,675)		(20,675)
Purchase of treasury stock (in shares)		(30,000)
Purchase of treasury stock	(5,329)				(5,329)
Stock-based plans (in shares)		29,000
Stock-based plans	(59)	$ (59)
Stock-based compensation expense	2,274	$ 2,274
Balance (in shares) at Sep. 30, 2021		27,530,000
Balance at Sep. 30, 2021	850,055	$ 130,832	1,492,200	(8,211)	(764,766)
Balance (in shares) at Jun. 30, 2021		27,531,000
Balance at Jun. 30, 2021	843,147	$ 128,617	1,482,220	(8,253)	(759,437)
Net income	65,025
Net pension and postretirement benefit gains, net of tax effect	83
Balance (in shares) at Dec. 31, 2021		27,534,000
Balance at Dec. 31, 2021	865,009	$ 133,419	1,504,535	(8,170)	(764,775)
Balance (in shares) at Sep. 30, 2021		27,530,000
Balance at Sep. 30, 2021	850,055	$ 130,832	1,492,200	(8,211)	(764,766)
Net income	34,370		34,370
Net pension and postretirement benefit gains, net of tax effect	41			41
Cash dividends - common stock	(22,035)		(22,035)
Purchase of treasury stock (in shares)		0
Purchase of treasury stock	(9)				(9)
Stock-based plans (in shares)		4,000
Stock-based plans	(2)	$ (2)
Stock-based compensation expense	2,589	$ 2,589
Balance (in shares) at Dec. 31, 2021		27,534,000
Balance at Dec. 31, 2021	$ 865,009	$ 133,419	1,504,535	(8,170)	(764,775)
Balance (in shares) at Jun. 30, 2022	27,520,237	27,520,000
Balance at Jun. 30, 2022	$ 844,687	$ 137,814	1,485,045	(11,172)	(767,000)
Net income	37,592		37,592
Net pension and postretirement benefit gains, net of tax effect	95			95
Cash dividends - common stock	(22,067)		(22,067)
Purchase of treasury stock (in shares)		0
Purchase of treasury stock	(84)				(84)
Stock-based plans (in shares)		34,000
Stock-based plans	(617)	$ (617)
Stock-based compensation expense	2,465	$ 2,465
Balance (in shares) at Sep. 30, 2022		27,554,000
Balance at Sep. 30, 2022	$ 862,071	$ 139,662	1,500,570	(11,077)	(767,084)
Balance (in shares) at Jun. 30, 2022	27,520,237	27,520,000
Balance at Jun. 30, 2022	$ 844,687	$ 137,814	1,485,045	(11,172)	(767,000)
Net income	77,565
Net pension and postretirement benefit gains, net of tax effect	$ 190
Balance (in shares) at Dec. 31, 2022	27,571,087	27,571,000
Balance at Dec. 31, 2022	$ 879,550	$ 140,660	1,517,081	(10,982)	(767,209)
Balance (in shares) at Sep. 30, 2022		27,554,000
Balance at Sep. 30, 2022	862,071	$ 139,662	1,500,570	(11,077)	(767,084)
Net income	39,973		39,973
Net pension and postretirement benefit gains, net of tax effect	95			95
Cash dividends - common stock	(23,462)		(23,462)
Purchase of treasury stock (in shares)		(1,000)
Purchase of treasury stock	(125)				(125)
Stock-based plans (in shares)		18,000
Stock-based plans	(1,801)	$ (1,801)
Stock-based compensation expense	$ 2,799	$ 2,799
Balance (in shares) at Dec. 31, 2022	27,571,087	27,571,000
Balance at Dec. 31, 2022	$ 879,550	$ 140,660	$ 1,517,081	$ (10,982)	$ (767,209)