SHAREHOLDERS' EQUITY (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Changes in shareholder's equity
Beginning balance			$ 1,048,157
Net earnings	$ 27,943	$ 23,173	60,548	$ 51,280
Ending balance	1,107,043	1,029,882	1,107,043	1,029,882
Common stock
Changes in shareholder's equity
Beginning balance	308	307	307	307
Stock plans			1
Ending balance	308	307	308	307
Additional paid-in-capital
Changes in shareholder's equity
Beginning balance	304,184	298,353	301,553	297,644
Stock plans	1,371	1,510	4,002	2,219
Ending balance	305,555	299,863	305,555	299,863
Retained earnings
Changes in shareholder's equity
Beginning balance	933,499	854,946	905,022	830,989
Net earnings	27,943	23,173	60,548	51,280
Dividends paid	(2,061)	(2,069)	(6,189)	(6,219)
Ending balance	959,381	876,050	959,381	876,050
Accumulated other comprehensive income (loss)
Changes in shareholder's equity
Beginning balance	(18,018)	(7,472)	(31,764)	(2,161)
Foreign currency translation	(821)	(11,905)	12,925	(17,216)
Ending balance	(18,839)	(19,377)	(18,839)	(19,377)
Treasury stock
Changes in shareholder's equity
Beginning balance	(139,178)	(124,961)	(126,961)	(107,083)
Share repurchases	(184)	(2,000)	(12,401)	(19,878)
Ending balance	$ (139,362)	$ (126,961)	$ (139,362)	$ (126,961)