CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Income Statement [Abstract]
Revenue	$ 287,863	$ 283,143
Cost of sales	164,959	154,461
Gross profit	122,904	128,682
Operating expenses:
Research, development and technical	12,428	12,811
Selling, general and administrative	55,920	54,439
Asset impairment charges	7,347	0
Total operating expenses	75,695	67,250
Operating income	47,209	61,432
Interest expense	9,608	11,920
Interest income	23	315
Other income (expense), net	1,452	(397)
Income before income taxes	39,076	49,430
Provision for income taxes	7,546	10,881
Net income	$ 31,530	$ 38,549
Basic earnings per share (in dollars per share)	$ 1.08	$ 1.32
Diluted earnings per share (in dollars per share)	$ 1.07	$ 1.30
Weighted average basic shares outstanding (in shares)	29,123,000	29,137,000
Weighted average diluted shares outstanding (in shares)	29,598,000	29,694,000