Quarterly Financial Information (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Quarterly Financial Information (Unaudited)
Net sales	$ 208,030	$ 172,665	$ 180,492	$ 171,728	$ 213,177	$ 178,259	$ 171,243	$ 163,365	$ 732,915	$ 726,044	$ 683,650
Net earnings (loss) from continuing operations	(21,808)	18,687	17,822	10,764	23,272	19,045	17,822	17,350	25,465	77,489	86,261
Net earnings from discontinued operations	502			76,013	1,586	1,022	975	(33)	(601)	3,550	5,875
Net earnings	$ (21,306)	$ 18,687	$ 17,822	$ 86,777	$ 24,858	$ 20,067	$ 18,797	$ 17,317	$ 101,980	$ 81,039	$ 92,136
Basic earnings per share:
Net earnings (loss) from continuing operations	$ (0.84)	$ 0.72	$ 0.69	$ 0.41	$ 0.90	$ 0.73	$ 0.69	$ 0.67	$ 0.98	$ 2.99	$ 3.33
Net earnings from discontinued operations	0.02			2.93	0.06	0.04	0.04		2.94	0.13	0.23
Basic - Net earnings	(0.82)	0.72	0.69	3.34	0.96	0.77	0.73	0.67	3.92	3.12	3.56
Diluted earnings per share:
Net earnings (loss) from continuing operations	(0.83)	0.72	0.68	0.41	0.89	0.73	0.68	0.66	0.97	2.97	3.31
Net earnings from discontinued operations	0.02			2.91	0.06	0.04	0.04		2.93	0.13	0.23
Net earnings (loss) - Diluted	(0.81)	0.72	0.68	3.32	0.95	0.77	0.72	0.66	3.90	3.10	3.54
Dividends declared per common share	0.08	0.08	0.08	0.08	0.08	0.08	0.08	0.08	$ 0.32	$ 0.32	$ 0.32
Common Stock per share:
High	95.60	94.24	107.10	93.21	85.86	82.70	71.29	71.47
Low	$ 78.30	$ 68.09	$ 62.64	$ 74.16	$ 73.04	$ 67.43	$ 62.91	$ 59.00