Condensed Statements of Shareholder's Equity Condensed Statements of Shareholders' Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Common Stock [Member] Stock Options and Stock Appreciation Rights [ Member]	Common Stock [Member] Performance Shares [Member]	Common Stock [Member] Restricted Stock Units (RSUs) [Member]	Additional Paid-in Capital [Member]	Additional Paid-in Capital [Member] Stock Options and Stock Appreciation Rights [ Member]	Additional Paid-in Capital [Member] Performance Shares [Member]	Additional Paid-in Capital [Member] Restricted Stock Units (RSUs) [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Treasury Stock [Member] Stock Options and Stock Appreciation Rights [ Member]	Treasury Stock [Member] Performance Shares [Member]	Treasury Stock [Member] Restricted Stock Units (RSUs) [Member]	Total Accumulated Other Comprehensive Income (Loss) [Member]	Parent [Member]	Parent [Member] Stock Options and Stock Appreciation Rights [ Member]	Parent [Member] Performance Shares [Member]	Parent [Member] Restricted Stock Units (RSUs) [Member]
Beginning balance, shares at Jun. 30, 2018		38,703
Beginning balance at Jun. 30, 2018		$ 10,000				$ 169,383				$ 1,129,678	$ (403,875)				$ (90,223)	$ 814,963
Net income	$ 48,938															48,938
Other comprehensive income (loss), net of tax															5,347	5,347
Cumulative effect of adopting accounting standards | Adjustments for New Accounting Pronouncement [Member]										3,056						3,056
Cash dividends										(13)						(13)
Exercise of stock appreciation rights and options, shares			17
Performance share awards, shares				18
Restricted stock units, shares					16
Additional Paid in Capital, Exercise of stock appreciation rights and options, Performance share awards, Restricted stock units							$ (855)	$ (844)	$ (760)
Exercise of stock appreciation rights and options												$ (210)
Performance share awards													$ (301)
Restricted stock units														$ (198)
Total Shareholders' Equity, Exercise of stock appreciation rights and options, Performance share awards, Restricted stock units																	$ (1,065)	$ (1,145)	$ (958)
Compensation expense						1,043	651									1,043	651
Other										24	(35)					(11)
Ending balance, shares at Sep. 30, 2018		38,754
Ending balance at Sep. 30, 2018		$ 10,000				168,618				1,181,683	(404,619)				(84,876)	870,806
Beginning balance, shares at Jun. 30, 2018		38,703
Beginning balance at Jun. 30, 2018		$ 10,000				169,383				1,129,678	(403,875)				(90,223)	814,963
Net income	87,655
Other comprehensive income (loss), net of tax	(4,409)														(4,409)
Ending balance, shares at Dec. 31, 2018		38,757
Ending balance at Dec. 31, 2018		$ 10,000				170,385				1,208,748	(404,586)				(94,632)	889,915
Beginning balance, shares at Sep. 30, 2018		38,754
Beginning balance at Sep. 30, 2018		$ 10,000				168,618				1,181,683	(404,619)				(84,876)	870,806
Net income	38,717															38,717
Other comprehensive income (loss), net of tax	$ (9,756)														(9,756)	(9,756)
Cash dividends										(11,651)						(11,651)
Restricted stock units, shares					3
Additional Paid in Capital, Exercise of stock appreciation rights and options, Performance share awards, Restricted stock units							(7)		(140)
Exercise of stock appreciation rights and options												1
Restricted stock units														31
Total Shareholders' Equity, Exercise of stock appreciation rights and options, Performance share awards, Restricted stock units																	(6)		(109)
Compensation expense						1,308	606									1,308	606
Other										(1)	1
Ending balance, shares at Dec. 31, 2018		38,757
Ending balance at Dec. 31, 2018		$ 10,000				170,385				1,208,748	(404,586)				(94,632)	889,915
Beginning balance, shares at Jun. 30, 2019	38,597	38,597
Beginning balance at Jun. 30, 2019	$ 897,034	$ 10,000				172,931				1,229,148	(415,159)				(99,886)	897,034
Net income	$ 38,799															38,799
Other comprehensive income (loss), net of tax															(5,247)	(5,247)
Cumulative effect of adopting accounting standards | Adjustments for New Accounting Pronouncement [Member]										(3,275)						(3,275)
Cash dividends										(20)						(20)
Exercise of stock appreciation rights and options, shares			5
Performance share awards, shares				36
Restricted stock units, shares					16
Additional Paid in Capital, Exercise of stock appreciation rights and options, Performance share awards, Restricted stock units							(177)	$ (1,540)	$ (631)
Exercise of stock appreciation rights and options												61
Performance share awards													$ 362
Restricted stock units														$ 200
Total Shareholders' Equity, Exercise of stock appreciation rights and options, Performance share awards, Restricted stock units																	(116)	$ (1,178)	$ (431)
Compensation expense						919	773									919	773
Stockholders' Equity, Other Shares		2
Other						(52)				(4)	23					(33)
Ending balance, shares at Sep. 30, 2019		38,656
Ending balance at Sep. 30, 2019		$ 10,000				172,223				1,264,648	(414,513)				(105,133)	927,225
Beginning balance, shares at Jun. 30, 2019	38,597	38,597
Beginning balance at Jun. 30, 2019	$ 897,034	$ 10,000				172,931				1,229,148	(415,159)				(99,886)	897,034
Net income	76,830
Other comprehensive income (loss), net of tax	$ 2,326														2,326
Ending balance, shares at Dec. 31, 2019	38,678	38,678
Ending balance at Dec. 31, 2019	$ 962,241	$ 10,000				173,677				1,290,685	(414,561)				(97,560)	962,241
Beginning balance, shares at Sep. 30, 2019		38,656
Beginning balance at Sep. 30, 2019		$ 10,000				172,223				1,264,648	(414,513)				(105,133)	927,225
Net income	38,031															38,031
Other comprehensive income (loss), net of tax	$ 7,573														7,573	7,573
Cash dividends										(12,017)						(12,017)
Exercise of stock appreciation rights and options, shares			22
Additional Paid in Capital, Exercise of stock appreciation rights and options, Performance share awards, Restricted stock units							(185)
Exercise of stock appreciation rights and options												$ (47)
Total Shareholders' Equity, Exercise of stock appreciation rights and options, Performance share awards, Restricted stock units																	(232)
Compensation expense						918	$ 721									918	$ 721
Other										23	(1)					22
Ending balance, shares at Dec. 31, 2019	38,678	38,678
Ending balance at Dec. 31, 2019	$ 962,241	$ 10,000				$ 173,677				$ 1,290,685	$ (414,561)				$ (97,560)	$ 962,241