Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Treasury Stock at Cost [Member]	Treasury Stock Held for Deferred Compensaton [Member]	Additional Paid-in Capital [Member]	Foreign Currency Translation Adjustments [Member]	Unrealized Derivative Gains (Losses) [Member]	Minimum Retirement Benefit Liability Adjustments [Member]	Total Accumulated Other Comprehensive (Loss) Earnings [Member]	Deferred Compensation [Member]	Retained Earnings [Member]
Balances at Sep. 30, 2019	$ 1,726,741	$ 106	$ (602,098)	$ (9,382)	$ 207,120	$ (53,235)	$ (4,955)	$ (45,116)	$ (103,306)	$ 9,382	$ 2,224,919
Balance, Common Stock, shares at Sep. 30, 2019		72,960,000
Balance, Treasury Stock, shares at Sep. 30, 2019			(11,040,000)
Balance, Treasury stock held for deferred compensation, shares at Sep. 30, 2019				(211,000)
Net earnings	53,373										53,373
Other comprehensive earnings (loss), net of tax	9,758					9,768	380	(390)	9,758
Cash dividends paid	(10,064)										(10,064)
Sales of treasury stock	7,558		$ 9,502		(1,944)
Sales of treasury stock, shares			226,000
Stock-based compensation	10,982				10,982
Purchases/transfers of stock by/to deferred compensation plan				$ (543)						543
Purchases and transfer of stock by/to deferred compensation plan, shares				(5,000)
Distribution of stock from deferred compensation plan				$ 14						(14)
Distribution of stock from deferred compensation plan, shares				1,000
Balances at Dec. 31, 2019	1,798,603	$ 106	$ (592,596)	$ (9,911)	216,158	(43,467)	(4,575)	(45,506)	(93,548)	9,911	2,268,483
Balance, Common Stock, shares at Dec. 31, 2019		72,960,000
Balance, Treasury Stock, shares at Dec. 31, 2019			(10,814,000)
Balance, Treasury stock held for deferred compensation, shares at Dec. 31, 2019				(215,000)
Cumulative effect from adoption | ASC 842 [Member]	255										255
Balances at Sep. 30, 2020	$ 1,992,677	$ 106	$ (577,476)	$ (9,222)	231,936	(40,691)	(20,457)	(28,646)	(89,794)	9,222	2,427,905
Balance, Common Stock, shares at Sep. 30, 2020	72,960,000	72,960,000
Balance, Treasury Stock, shares at Sep. 30, 2020	(10,277,000)		(10,277,000)
Balance, Treasury stock held for deferred compensation, shares at Sep. 30, 2020	(199,000)			(199,000)
Net earnings	$ 41,570										41,570
Other comprehensive earnings (loss), net of tax	9,478					21,239	(11,038)	(723)	9,478
Cash dividends paid	(5,102)										(5,102)
Sales of treasury stock	11,370		$ 12,381		(1,011)
Sales of treasury stock, shares			285,000
Stock-based compensation	13,469				13,469
Purchases/transfers of stock by/to deferred compensation plan				$ (276)						276
Purchases and transfer of stock by/to deferred compensation plan, shares				(3,000)
Distribution of stock from deferred compensation plan				$ 13						(13)
Distribution of stock from deferred compensation plan, shares				1,000
Balances at Dec. 31, 2020	$ 2,063,462	$ 106	$ (565,095)	$ (9,485)	$ 244,394	$ (19,452)	$ (31,495)	$ (29,369)	$ (80,316)	$ 9,485	$ 2,464,373
Balance, Common Stock, shares at Dec. 31, 2020	72,960,000	72,960,000
Balance, Treasury Stock, shares at Dec. 31, 2020	(9,992,000)		(9,992,000)
Balance, Treasury stock held for deferred compensation, shares at Dec. 31, 2020	(201,000)			(201,000)