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 (loss)	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, 2020		27,524,000
Balance at Jun. 30, 2020	783,300	$ 125,153	1,421,121	(12,070)	(750,904)
Net income (loss)	110,606
Net pension and postretirement benefit gains, net of tax effect	282
Balance (in shares) at Mar. 31, 2021		27,545,000
Balance at Mar. 31, 2021	831,113	$ 127,277	1,471,151	(11,788)	(755,527)
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)
Net income (loss)	44,630		44,630
Net pension and postretirement benefit gains, net of tax effect	94			94
Cash dividends - common stock	(20,655)		(20,655)
Purchase of treasury stock (in shares)		0
Purchase of treasury stock	(4)				(4)
Stock-based plans (in shares)		7,000
Stock-based plans	(581)	$ (581)
Stock-based compensation expense	1,770	$ 1,770
Balance (in shares) at Dec. 31, 2020		27,547,000
Balance at Dec. 31, 2020	826,360	$ 126,260	1,462,905	(11,882)	(750,923)
Net income (loss)	28,897		28,897
Net pension and postretirement benefit gains, net of tax effect	94			94
Cash dividends - common stock	(20,651)		(20,651)
Purchase of treasury stock (in shares)		(26,000)
Purchase of treasury stock	(4,604)				(4,604)
Stock-based plans (in shares)		24,000
Stock-based plans	(675)	$ (675)
Stock-based compensation expense	1,692	$ 1,692
Balance (in shares) at Mar. 31, 2021		27,545,000
Balance at Mar. 31, 2021	$ 831,113	$ 127,277	1,471,151	(11,788)	(755,527)
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 (loss)	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	27,531,040	27,531,000
Balance at Jun. 30, 2021	$ 843,147	$ 128,617	1,482,220	(8,253)	(759,437)
Net income (loss)	60,542
Net pension and postretirement benefit gains, net of tax effect	$ 126
Balance (in shares) at Mar. 31, 2022	27,523,562	27,524,000
Balance at Mar. 31, 2022	$ 838,622	$ 135,645	1,478,026	(8,127)	(766,922)
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 (loss)	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)
Net income (loss)	(4,483)		(4,483)
Net pension and postretirement benefit gains, net of tax effect	43			43
Cash dividends - common stock	(22,026)		(22,026)
Purchase of treasury stock (in shares)		(14,000)
Purchase of treasury stock	(2,147)				(2,147)
Stock-based plans (in shares)		4,000
Stock-based plans	(295)	$ (295)
Stock-based compensation expense	$ 2,521	$ 2,521
Balance (in shares) at Mar. 31, 2022	27,523,562	27,524,000
Balance at Mar. 31, 2022	$ 838,622	$ 135,645	$ 1,478,026	$ (8,127)	$ (766,922)