Quarterly Financial Information (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Net sales	$ 159,505	$ 140,191	$ 138,930	$ 132,833	$ 153,612	$ 134,191	$ 128,941	$ 120,547	$ 571,459	$ 537,291	$ 531,120
Net earnings from continuing operations	16,915	11,528	8,610	8,829	12,983	10,748	7,982	10,023	45,882	41,736	42,613
Net earnings (loss) from discontinued operations	0	0	0	0	0	1,148	(372)	0	0	0	9,858
Net earnings	$ 16,915	$ 11,528	$ 8,610	$ 8,829	$ 12,983	$ 11,896	$ 7,610	$ 10,023	$ 45,882	$ 42,512	$ 410
Basic earnings (loss) per share:
Net earnings from continuing operations	$ 0.66	$ 0.45	$ 0.33	$ 0.34	$ 0.50	$ 0.41	$ 0.31	$ 0.38	$ 1.78	$ 1.60	$ 1.61
Net earnings (loss) from discontinued operations	0	0	0	0	0	0.04	(0.01)	0	0	0.03	(1.60)
Net earnings (loss)	0.66	0.45	0.33	0.34	0.50	0.45	0.30	0.38	1.78	1.63	0.01
Diluted earnings (loss) per share:
Net earnings from continuing operations	0.65	0.44	0.33	0.34	0.50	0.41	0.30	0.38	1.77	1.59	1.60
Net earnings (loss) from discontinued operations	0	0	0	0	0	0.04	(0.01)	0	0	0.03	(1.58)
Net earnings	0.65	0.44	0.33	0.34	0.50	0.45	0.29	0.38	1.77	1.62	0.02
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