Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total stockholders equity	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Total Accumulated Other Comprehensive (Loss) Earnings [Member]	Foreign Currency Translation Adjustments [Member]	Unrealized Derivative Gains (Losses) [Member]	Minimum Retirement Benefit Liability Adjustments [Member]	Deferred Compensation in Equity [Member]	Retained Earnings [Member]	Treasury Stock at Cost [Member]	Treasury Stock Held for Deferred Compensaton [Member]	Total
Balances at Sep. 30, 2016	$ 1,212,595		$ 106	$ 141,570	$ (65,705)	$ (25,971)	$ 179	$ (39,913)	$ 5,089	$ 1,649,506	$ (512,882)	$ (5,089)
Balance, Preferred Stock, shares at Sep. 30, 2016		0
Balance, Common Stock, shares at Sep. 30, 2016			72,960
Balance, Treasury Stock, shares at Sep. 30, 2016											(11,374)
Balance, Treasury stock held for deferred compensation, Shares at Sep. 30, 2016												(157)
Net earnings	46,548									46,548			$ 46,548
Other comprehensive income (loss), net of tax	(13,863)				(13,863)	(15,111)	(11)	1,259
Cash dividends paid	(6,779)									(6,779)
Purchases of treasury stock	(24,004)										$ (24,004)
Purchases of treasury stock, shares											(350)
Sales of treasury stock	4,843			(907)							$ 5,750
Sales of treasury stock, shares											139
Common shares issued from treasury stock to settle employee liabilities	1,767			740					1,767		$ 1,027	$ (1,767)	1,767
Common shares issued from treasury stock to settle employee liabilities, shares											26	(26)
Stock-based compensation	1,261			1,261
Purchases of stock by deferred compensation plan									37			$ (37)
Distribution of stock from deferred compensation plan									(4)			4
Balances at Dec. 31, 2016	1,222,368		$ 106	142,664	(79,568)	(41,082)	168	(38,654)	6,889	1,689,275	$ (530,109)	$ (6,889)
Balance, Preferred Stock, shares at Dec. 31, 2016		0
Balance, Common Stock, shares at Dec. 31, 2016			72,960
Balance, Treasury Stock, shares at Dec. 31, 2016											(11,559)
Balance, Treasury stock held for deferred compensation, Shares at Dec. 31, 2016												(183)
Balances at Sep. 30, 2017	1,371,383		$ 106	163,836	(53,186)	(27,280)	135	(26,041)	7,135	1,820,268	$ (559,641)	$ (7,135)	$ 1,371,383
Balance, Preferred Stock, shares at Sep. 30, 2017		0											0
Balance, Common Stock, shares at Sep. 30, 2017			72,960										72,960
Balance, Treasury Stock, shares at Sep. 30, 2017											(11,739)		(11,739)
Balance, Treasury stock held for deferred compensation, Shares at Sep. 30, 2017												(186)	(186)
Net earnings	18,260									18,260			$ 18,260
Other comprehensive income (loss), net of tax	4,747				4,747	4,547	(11)	211
Cash dividends paid	(7,656)									(7,656)
Sales of treasury stock	1,389			214							$ 1,175
Sales of treasury stock, shares											33
Common shares issued from treasury stock to settle employee liabilities													0
Stock-based compensation	12,423			12,423
Purchases of stock by deferred compensation plan									1,041			$ (1,041)
Purchases of stock by deferred compensation plan, shares												(14)
Distribution of stock from deferred compensation plan									(3)			$ 3
Balances at Dec. 31, 2017	$ 1,400,546		$ 106	$ 176,473	$ (48,439)	$ (22,733)	$ 124	$ (25,830)	$ 8,173	$ 1,830,872	$ (558,466)	$ (8,173)	$ 1,400,546
Balance, Preferred Stock, shares at Dec. 31, 2017		0											0
Balance, Common Stock, shares at Dec. 31, 2017			72,960										72,960
Balance, Treasury Stock, shares at Dec. 31, 2017											(11,706)		(11,706)
Balance, Treasury stock held for deferred compensation, Shares at Dec. 31, 2017												(200)	(200)