SHAREHOLDERS' EQUITY (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Jun. 30, 2021	Sep. 30, 2020	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Changes in shareholder's equity
Beginning Balance		$ 943,457		$ 959,026
Net earnings	$ 14,909		$ 18,687	43,131	$ 123,286
Ending Balance	1,004,854	959,026	943,457	1,004,854	943,457
Common Stock
Changes in shareholder's equity
Beginning Balance	306	307	306	306	306
Stock plans	1		1	1	1
Ending Balance	307	306	307	307	307
Additional paid-in-capital
Changes in shareholder's equity
Beginning Balance	295,796	292,631	294,787	293,682	292,408
Stock plans	782		(2,156)	2,896	223
Ending Balance	296,578	293,682	292,631	296,578	292,631
Retained Earnings
Changes in shareholder's equity
Beginning Balance	799,884	801,787	785,184	775,829	684,741
Net earnings	14,909		18,687	43,131	123,286
Dividends paid	(2,084)		(2,084)	(6,251)	(6,240)
Ending Balance	812,709	775,829	801,787	812,709	801,787
Accumulated other comprehensive income (loss)
Changes in shareholder's equity
Beginning Balance	1,808	(44,134)	(46,936)	(3,657)	(43,974)
Foreign currency translation	535		2,802	6,000	(160)
Ending Balance	2,343	(3,657)	(44,134)	2,343	(44,134)
Treasury Stock
Changes in shareholder's equity
Beginning Balance	(107,134)	(107,134)	(107,134)	(107,134)	(107,259)
Issued under stock plans	51			51	125
Ending Balance	$ (107,083)	$ (107,134)	$ (107,134)	$ (107,083)	$ (107,134)

Amount of paid and unpaid cash dividends declared for classes of stock, for example, but not limited to, common and preferred.

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