CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Treasury Stock [Member]	Total
Beginning Balance at Sep. 30, 2016	$ 304	$ 290,588	$ 471,272	$ (39,283)	$ (107,772)	$ 615,109
Balance (in shares) at Sep. 30, 2016	30,364
Comprehensive income (loss):
Net earnings	$ 0	0	53,703	0	0	53,703
Translation adjustments, net of tax	0	0	0	6,383	0	6,383
Net unrecognized actuarial (loss) gain, net of tax	0	0	0	5,573	0	5,573
Forward exchange contracts, net of tax	0	0	0	19	0	19
Cash dividends declared	0	0	(8,257)	0	0	(8,257)
Stock options and stock compensation plans, net of tax	$ 1	(803)	0	0	190	(612)
Stock options and stock compensation plans, net of tax (in shares)	105
Ending Balance at Sep. 30, 2017	$ 305	289,785	516,718	(27,308)	(107,582)	671,918
Ending Balance (in shares) at Sep. 30, 2017	30,469
Comprehensive income (loss):
Net earnings	$ 0	0	92,136	0	0	92,136
Translation adjustments, net of tax	0	0	0	(2,254)	0	(2,254)
Net unrecognized actuarial (loss) gain, net of tax	0	0	0	(2,003)	0	(2,003)
Forward exchange contracts, net of tax	0	0	0	37	0	37
Cash dividends declared	0	0	(8,278)	0	0	(8,278)
Reclassification from accumulated other comprehensive loss as a result of the adoption of new accounting standard ASU 2018-02	0	0	6,261	0	0	6,261
Stock options and stock compensation plans, net of tax	$ 0	1,405	0	0	188	1,593
Stock options and stock compensation plans, net of tax (in shares)	66
Ending Balance at Sep. 30, 2018	$ 305	291,190	606,837	(31,528)	(107,394)	759,410
Ending Balance (in shares) at Sep. 30, 2018	30,535
Comprehensive income (loss):
Net earnings	$ 0	0	81,039	0	0	81,039
Translation adjustments, net of tax	0	0	0	(6,474)	0	(6,474)
Net unrecognized actuarial (loss) gain, net of tax	0	0	0	(6,066)	0	(6,066)
Forward exchange contracts, net of tax	0	0	0	94	0	94
Cash dividends declared	0	0	(8,302)	0	0	(8,302)
Reclassification from accumulated other comprehensive loss as a result of the adoption of new accounting standard ASU 2018-02						(6,300)
Stock options and stock compensation plans, net of tax	$ 1	1,218	0	0	135	1,354
Stock options and stock compensation plans, net of tax (in shares)	62
Ending Balance at Sep. 30, 2019	$ 306	$ 292,408	684,741	$ (43,974)	$ (107,259)	826,222
Ending Balance (in shares) at Sep. 30, 2019	30,597
Comprehensive income (loss):
Adoption of new accounting standard ASU 2014-09			$ 5,167			$ 5,167