CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Treasury Stock [Member]
Balance at Sep. 30, 2015	$ 584,182	$ 304	$ 286,485	$ 433,632	$ (32,538)	$ (103,701)
Balance (in shares) at Sep. 30, 2015		30,359
Comprehensive income (loss):
Net earnings	45,882	$ 0	0	45,882	0	0
Translation adjustments, net of tax	(1,462)	0	0	0	(1,462)	0
Net unrecognized actuarial (loss) gain, net of tax	(5,250)	0	0	0	(5,250)	0
Forward exchange contracts, net of tax	(33)	0	0	0	(33)	0
Cash dividends declared	(8,242)	0	0	(8,242)	0	0
Stock options and stock compensation plans, net of tax	4,335	$ 0	4,103	0	0	232
Stock options and stock compensation plans, net of tax (in shares)		5
Purchases into treasury	(4,303)	$ 0	0	0	0	(4,303)
Ending Balance at Sep. 30, 2016	615,109	$ 304	290,588	471,272	(39,283)	(107,772)
Ending Balance (in shares) at Sep. 30, 2016		30,364
Comprehensive income (loss):
Net earnings	53,703	$ 0	0	53,703	0	0
Translation adjustments, net of tax	6,383	0	0	0	6,383	0
Net unrecognized actuarial (loss) gain, net of tax	5,573	0	0	0	5,573	0
Forward exchange contracts, net of tax	19	0	0	0	19	0
Cash dividends declared	(8,257)	0	0	(8,257)	0	0
Stock options and stock compensation plans, net of tax	(612)	$ 1	(803)	0	0	190
Stock options and stock compensation plans, net of tax (in shares)		105
Ending Balance at Sep. 30, 2017	671,918	$ 305	289,785	516,718	(27,308)	(107,582)
Ending Balance (in shares) at Sep. 30, 2017		30,469
Comprehensive income (loss):
Net earnings	92,136	$ 0	0	92,136	0	0
Translation adjustments, net of tax	(2,254)	0	0	0	(2,254)	0
Net unrecognized actuarial (loss) gain, net of tax	(2,003)	0	0	0	(2,003)	0
Forward exchange contracts, net of tax	37	0	0	0	37	0
Cash dividends declared	(8,278)	0	0	(8,278)	0	0
Reclassification from accumulated other comprehensive loss as a result of the adoption of a new accounting standard	6,261			6,261
Stock options and stock compensation plans, net of tax	1,593	$ 0	1,405	0	0	188
Stock options and stock compensation plans, net of tax (in shares)		66
Ending Balance at Sep. 30, 2018	$ 759,410	$ 305	$ 291,190	$ 606,837	$ (31,528)	$ (107,394)
Ending Balance (in shares) at Sep. 30, 2018		30,535