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, 2020		27,524,000
Balance at Jun. 30, 2020	$ 783,300	$ 125,153	$ 1,421,121	$ (12,070)	$ (750,904)
Net income	37,079		37,079
Net pension and postretirement benefit gains, net of tax effect	94			94
Cash dividends - common stock	(19,270)		(19,270)
Purchase of treasury stock (in shares)		0
Purchase of treasury stock	(15)				(15)
Stock-based plans (in shares)		16,000
Stock-based plans	(1,854)	$ (1,854)
Stock-based compensation expense	1,772	$ 1,772
Balance (in shares) at Sep. 30, 2020		27,540,000
Balance at Sep. 30, 2020	$ 801,106	$ 125,071	1,438,930	(11,976)	(750,919)
Balance (in shares) at Jun. 30, 2021	27,531,040	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	27,529,867	27,530,000
Balance at Sep. 30, 2021	$ 850,055	$ 130,832	$ 1,492,200	$ (8,211)	$ (764,766)