Business Acquisitions (Schedule of Unaudited Pro Forma Results) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Business Acquisition [Line Items]
Net sales	$ 719,359	$ 588,117	$ 548,249	$ 470,148	$ 606,788	$ 548,622	$ 500,381	$ 442,894	$ 2,325,873	$ 2,098,685	$ 2,023,078
Net earnings	$ 74,512	$ 49,117	$ 38,489	$ 18,260	$ 62,228	$ 53,626	$ 38,105	$ 46,548	$ 180,378	$ 200,507	$ 180,838
Basic earnings per share	$ 1.21	$ 0.80	$ 0.63	$ 0.30	$ 1.02	$ 0.87	$ 0.62	$ 0.76	$ 2.93	$ 3.27	$ 2.92
Diluted earnings per share	$ 1.16	$ 0.77	$ 0.60	$ 0.29	$ 0.98	$ 0.85	$ 0.60	$ 0.73	$ 2.82	$ 3.16	$ 2.85
Business Acquisition, Acquiree - L'Orange [Member]
Pro forma
Net earnings									$ 221,193	$ 173,962
Net sales									$ 2,549,874	$ 2,380,572
Basic earnings per share									$ 3.60	$ 2.83
Diluted earnings per share									$ 3.46	$ 2.74