Business Acquisitions (Schedule of Unaudited Pro Forma Results) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Net sales	$ 562,625	$ 494,810	$ 493,222	$ 487,646	$ 565,447	$ 524,284	$ 482,467	$ 429,042	$ 2,038,303	$ 2,001,240	$ 1,935,976
Net earnings	$ 50,060	$ 43,753	$ 43,855	$ 43,784	$ 51,662	$ 46,001	$ 44,798	$ 23,383	$ 181,452	$ 165,844	$ 145,942
Basic earnings per share	$ 0.79	$ 0.68	$ 0.67	$ 0.67	$ 0.79	$ 0.70	$ 0.67	$ 0.35	$ 2.81	$ 2.50	$ 2.13
Diluted earnings per share	$ 0.77	$ 0.66	$ 0.66	$ 0.66	$ 0.77	$ 0.69	$ 0.66	$ 0.34	$ 2.75	$ 2.45	$ 2.10
Business Acquisition, Acquiree - Duarte Business [Member]
Net sales											$ 1,935,976
Net earnings											$ 145,942
Basic earnings per share											$ 2.13
Diluted earnings per share											$ 2.10
Pro forma
Net sales											$ 1,966,376
Net earnings											$ 152,431
Basic earnings per share											$ 2.23
Diluted earnings per share											$ 2.19